

기계 번역으로 제공되는 번역입니다. 제공된 번역과 원본 영어의 내용이 상충하는 경우에는 영어 버전이 우선합니다.

# 샘플 애플리케이션 자습서를 사용하여 Amazon QLDB 시작하기
<a name="getting-started-sample-app"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 자습서에서는 AWS SDK와 함께 Amazon QLDB 드라이버를 사용하여 QLDB 원장을 생성하고 샘플 데이터로 채웁니다. 드라이버를 사용하면 애플리케이션이 트랜잭션 데이터 API를 사용하여 QLDB와 상호 작용할 수 있습니다. AWS SDK는 QLDB 리소스 관리 API와의 상호 작용을 지원합니다.

이 시나리오에서 생성하는 샘플 원장은 차량 등록에 대한 전체 기록 정보를 추적하는 자동차 부서(DMV) 데이터베이스입니다. 다음 항목에서는 차량 등록을 추가하고, 수정하고, 해당 등록의 변경 기록을 보는 방법을 설명합니다. 또한 이 안내서는 등록 문서를 암호적으로 검증하는 방법을 보여주며, 리소스를 정리하고 샘플 원장을 삭제하는 것으로 마무리합니다.

샘플 애플리케이션 자습서는 다음 프로그래밍 언어로 제공됩니다.

**Topics**
+ [Java 자습서](getting-started.java.tutorial.md)
+ [Node.js 자습서](getting-started.nodejs.tutorial.md)
+ [Python 자습서](getting-started.python.tutorial.md)

# Amazon QLDB Java 자습서
<a name="getting-started.java.tutorial"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 자습서 샘플 애플리케이션 구현에서는 Amazon QLDB 드라이버 AWS SDK for Java 를와 함께 사용하여 QLDB 원장을 생성하고 샘플 데이터로 채웁니다.

이 자습서로 학습하면서 관리 API 작업에 대해서 [AWS SDK for Java API 참조](https://docs.aws.amazon.com/sdk-for-java/latest/reference/)를 참조할 수 있습니다. 트랜잭션 데이터 작업의 경우 [Java용 QLDB 드라이버 API 참조](https://javadoc.io/doc/software.amazon.qldb/amazon-qldb-driver-java/latest/index.html)를 참조할 수 있습니다.

**참고**  
해당하는 경우 일부 자습서 단계에는 Java용 QLDB 드라이버의 지원되는 각 메이저 버전마다 서로 다른 명령 또는 코드 예제가 있습니다.

**Topics**
+ [Amazon QLDB Java 샘플 애플리케이션 설치](sample-app.java.md)
+ [1단계: 새 원장 생성](getting-started.java.step-1.md)
+ [2단계: 원장과의 연결을 테스트](getting-started.java.step-2.md)
+ [3단계: 테이블, 인덱스 및 샘플 데이터 생성](getting-started.java.step-3.md)
+ [4단계: 원장에서 테이블 쿼리](getting-started.java.step-4.md)
+ [5단계: 원장의 문서 수정](getting-started.java.step-5.md)
+ [6단계: 문서의 개정 기록 보기](getting-started.java.step-6.md)
+ [7단계: 원장에 있는 문서 검증](getting-started.java.step-7.md)
+ [8단계: 원장의 저널 데이터 내보내기 및 검증](getting-started.java.step-8.md)
+ [9단계(선택 사항): 리소스 정리](getting-started.java.step-9.md)

# Amazon QLDB Java 샘플 애플리케이션 설치
<a name="sample-app.java"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 섹션에서는 단계별 Java 자습서를 위해 제공된 Amazon QLDB 샘플 애플리케이션을 설치하고 실행하는 방법을 설명합니다. 이 샘플 애플리케이션의 사용 사례는 차량 등록에 대한 전체 기록 정보를 추적하는 자동차 부서(DMV) 데이터베이스입니다.

Java용 DMV 샘플 애플리케이션은 GitHub 리포지토리 [aws-samples/amazon-qldb-dmv-sample-java](https://github.com/aws-samples/amazon-qldb-dmv-sample-java)의 오픈 소스입니다.

## 사전 조건
<a name="sample-app.java.prereqs"></a>

시작하기 전에 Java [사전 조건](getting-started.java.md#getting-started.java.prereqs)용 QLDB 드라이버를 완료했는지 확인합니다. 다음 내용이 포함됩니다:

1. 가입합니다 AWS.

1. 적절한 QLDB 권한을 가진 사용자를 생성합니다. 이 자습서의 모든 단계를 완료하려면 QLDB API를 통해 원장 리소스에 대한 전체 관리 액세스 권한이 필요합니다.

1. 이외의 IDE를 사용하는 경우 Java를 AWS Cloud9설치하고 개발을 위한 프로그래밍 방식 액세스 권한을 부여합니다.

## 설치
<a name="sample-app.java.install"></a>

다음 단계는 로컬 개발 환경에서 샘플 애플리케이션을 다운로드하고 설정하는 방법을 설명합니다. 또는를 IDE AWS Cloud9 로 사용하고 CloudFormation 템플릿을 사용하여 개발 리소스를 프로비저닝하여 샘플 애플리케이션 설정을 자동화할 수 있습니다.

### 로컬 개발 환경
<a name="sample-app.java.local-ide"></a>

이 지침은 자체 리소스 및 개발 환경을 사용하여 QLDB Java 샘플 애플리케이션을 다운로드하고 설치하는 방법을 설명합니다.

**샘플 애플리케이션을 다운로드하여 실행하려면**

1. 다음 명령을 입력하여 GitHub에서 샘플 애플리케이션을 복제합니다.

------
#### [ 2.x ]

   ```
   git clone https://github.com/aws-samples/amazon-qldb-dmv-sample-java.git
   ```

------
#### [ 1.x ]

   ```
   git clone -b v1.2.0 https://github.com/aws-samples/amazon-qldb-dmv-sample-java.git
   ```

------

   이 패키지에는 Gradle 구성 및 [Java 자습서](getting-started.java.tutorial.md)의 전체 코드가 포함되어 있습니다.

1. 제공된 애플리케이션을 로드하고 실행합니다.
   + Eclipse를 사용하는 경우:

     1. Eclipse를 시작하고 **Eclipse** 메뉴에서 **파일**, **가져오기**, **기존 Gradle 프로젝트**를 차례로 선택합니다.

     1. 프로젝트 루트 디렉터리에서 `build.gradle` 파일이 포함된 애플리케이션 디렉터리를 찾아 선택합니다. 그런 다음 **완료**를 선택하여 기본 Gradle 설정을 가져오기에 사용합니다.

     1. 예를 들어, `ListLedgers` 프로그램을 실행해 볼 수 있습니다. `ListLedgers.java` 파일에 대한 컨텍스트 메뉴를 열고(마우스 오른쪽 버튼 클릭) **Java 애플리케이션으로 실행**을 선택합니다.
   + IntelliJ를 사용하는 경우:

     1. IntelliJ를 시작하고 **IntelliJ** 메뉴에서 **파일**을 선택한 다음 **열기**를 선택합니다.

     1. 프로젝트 루트 디렉터리에서 `build.gradle` 파일이 포함된 애플리케이션 디렉터리를 찾아 선택합니다. 그 다음에 **확인**을 선택합니다. 기본 설정을 유지하고 **확인**을 다시 선택합니다.

     1. 예를 들어, `ListLedgers` 프로그램을 실행해 볼 수 있습니다. `ListLedgers.java` 파일에 대한 컨텍스트 메뉴를 열고(마우스 오른쪽 버튼 클릭) **'ListLedgers’ 실행**을 선택합니다.

1. [1단계: 새 원장 생성](getting-started.java.step-1.md)로 진행하여 자습서를 시작하고 원장을 생성하세요.

### AWS Cloud9
<a name="sample-app.java.cfn-ac9"></a>

이 지침에서는 [AWS Cloud9](https://aws.amazon.com/cloud9)을 IDE로 사용하여 Java용 Amazon QLDB 차량 등록 샘플 애플리케이션을 자동으로 설정하는 방법을 설명합니다. 이 안내서에서는 [CloudFormation](https://aws.amazon.com/cloudformation) 템플릿을 사용하여 개발 리소스를 프로비저닝합니다.

에 대한 자세한 내용은 [AWS Cloud9 사용 설명서를](https://docs.aws.amazon.com/cloud9/latest/user-guide/) AWS Cloud9참조하세요. CloudFormation에 대한 자세한 내용은 [AWS CloudFormation 사용 설명서](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/)를 참조하세요.

**Topics**
+ [1부: 리소스 프로비저닝](#sample-app.java.cfn-ac9.step-1)
+ [2부: IDE 설정](#sample-app.java.cfn-ac9.step-2)
+ [3부: QLDB DMV 샘플 애플리케이션 실행](#sample-app.java.cfn-ac9.step-3)

#### 1부: 리소스 프로비저닝
<a name="sample-app.java.cfn-ac9.step-1"></a>

이 첫 번째 단계에서는 CloudFormation 를 사용하여 Amazon QLDB 샘플 애플리케이션을 사용하여 개발 환경을 설정하는 데 필요한 리소스를 프로비저닝합니다.

**CloudFormation 콘솔을 열고 QLDB 샘플 애플리케이션 템플릿을 로드하려면**

1. 에 로그인 AWS Management Console 하고 [https://console.aws.amazon.com/cloudformation](https://console.aws.amazon.com/cloudformation/) CloudFormation 콘솔을 엽니다.

   QLDB를 지원하는 리전으로 전환합니다. 전체 목록은 *AWS 일반 참조*에서 [Amazon QLDB 엔드포인트 및 할당량](https://docs.aws.amazon.com/general/latest/gr/qldb.html)을 참조하세요. 의 다음 스크린샷은 미국 동부(버지니아 북부)를 선택한 로 AWS Management Console 보여줍니다 AWS 리전.  
![\[AWS Management Console 미국 동부(버지니아 북부)를 선택한 로 표시합니다 AWS 리전.\]](http://docs.aws.amazon.com/ko_kr/qldb/latest/developerguide/images/cfn-ac9/aws-region-us-east-1.png)

1.  CloudFormation 콘솔에서 **스택 생성을** 선택한 다음 **새 리소스 사용(표준)**을 선택합니다.

1. **템플릿 지정** 아래 **스택 생성** 페이지에서 **Amazon S3 URL**을 선택합니다.

1. 다음 URL을 입력하고 **다음**을 선택합니다.

   ```
   https://amazon-qldb-assets.s3.amazonaws.com/templates/QLDB-DMV-SampleApp.yml
   ```

1. **qldb-sample-app**와 같은 **스택 이름**을 입력한 후 **다음**을 선택합니다.

1. 원하는 대로 태그를 추가하고 기본 옵션을 유지할 수 있습니다. 그런 다음 **다음**을 선택합니다.

1. 스택 설정을 검토하고 **스택 생성**을 선택합니다. CloudFormation 스크립트를 완료하는 데 몇 분 정도 걸릴 수 있습니다.

   이 스크립트는이 자습서에서 QLDB 샘플 애플리케이션을 실행하는 데 사용하는 연결된 Amazon Elastic Compute Cloud(Amazon EC2) 인스턴스로 AWS Cloud9 환경을 프로비저닝합니다. 또한 [aws-samples/amazon-qldb-dmv-sample-java](https://github.com/aws-samples/amazon-qldb-dmv-sample-java/) 리포지토리를 GitHub에서 AWS Cloud9 개발 환경으로 복제합니다.

#### 2부: IDE 설정
<a name="sample-app.java.cfn-ac9.step-2"></a>

이 단계에서는 클라우드 개발 환경 설정을 완료합니다. 제공된 쉘 스크립트를 다운로드하고 실행하여 샘플 애플리케이션의 종속성을 사용하여 AWS Cloud9 IDE를 설정합니다.

**AWS Cloud9 환경을 설정하려면**

1. [https://console.aws.amazon.com/cloud9/](https://console.aws.amazon.com/cloud9/) AWS Cloud9 콘솔을 엽니다.

1. **사용자 환경**에서 **QLDB DMV 샘플 애플리케이션**이라는 환경 이름의 카드를 찾아 **IDE 열기**를 선택합니다. 기본 EC2 인스턴스가 시작될 때 환경을 로드하는 데 1분 정도 걸릴 수 있습니다.

    AWS Cloud9 환경은 자습서를 실행하는 데 필요한 시스템 종속성으로 사전 구성되어 있습니다. 콘솔의 **환경** 탐색 창에 `QLDB DMV Sample Application`로 이름이 지정된 폴더가 표시되는지 확인합니다. AWS Cloud9 콘솔의 다음 스크린샷은 QLDB DMV 샘플 애플리케이션 환경 폴더 창을 보여줍니다.  
![\[AWS Cloud9 QLDB DMV 샘플 애플리케이션 환경 폴더 창을 보여주는 콘솔.\]](http://docs.aws.amazon.com/ko_kr/qldb/latest/developerguide/images/cfn-ac9/cloud9-folders.png)

   탐색 창이 보이지 않으면 콘솔 왼쪽에 있는 **환경** 탭을 전환하세요. 패널에 폴더가 보이지 않는 경우, 설정 아이콘(![\[Settings icon\]](http://docs.aws.amazon.com/ko_kr/qldb/latest/developerguide/images/settings.png))을 사용하여 **환경 루트 표시**를 활성화하세요.

1. 콘솔 하단 창에 열린 `bash` 터미널 창이 보일 것입니다. 이 화면이 보이지 않으면 콘솔 상단의 **창** 메뉴에서 **새 터미널**을 선택합니다.

1. 그런 다음 설치 스크립트를 다운로드하여 실행하여 OpenJDK 8을 설치하고 해당하는 경우 Git 리포지토리에서 적절한 브랜치를 확인합니다. 이전 단계에서 생성한 AWS Cloud9 터미널에서 다음 두 명령을 순서대로 실행합니다.

------
#### [ 2.x ]

   ```
   aws s3 cp s3://amazon-qldb-assets/setup-scripts/dmv-setup-v2.sh .
   ```

   ```
   sh dmv-setup-v2.sh
   ```

------
#### [ 1.x ]

   ```
   aws s3 cp s3://amazon-qldb-assets/setup-scripts/dmv-setup.sh .
   ```

   ```
   sh dmv-setup.sh
   ```

------

   완료되면 터미널에서 다음 메시지가 출력됩니다.

   ```
   ** DMV Sample App setup completed , enjoy!! **
   ```

1. 잠시 시간을 내어 샘플 애플리케이션 코드 AWS Cloud9, 특히 디렉터리 경로에서 샘플 애플리케이션 코드를 찾아보십시오`src/main/java/software/amazon/qldb/tutorial`.

#### 3부: QLDB DMV 샘플 애플리케이션 실행
<a name="sample-app.java.cfn-ac9.step-3"></a>

이 단계에서는를 사용하여 Amazon QLDB DMV 샘플 애플리케이션 작업을 실행하는 방법을 알아봅니다 AWS Cloud9. 샘플 코드를 실행하려면 *2부: IDE 설정*에서와 같이 AWS Cloud9 터미널로 돌아가거나 새 터미널 창을 생성합니다.

**샘플 애플리케이션을 실행하려면**

1. 터미널에서 다음 명령을 실행하여 프로젝트 루트 디렉터리로 전환합니다.

   ```
   cd ~/environment/amazon-qldb-dmv-sample-java
   ```

   다음 디렉터리 경로에서 예제를 실행하고 있는지 확인하세요.

   ```
   /home/ec2-user/environment/amazon-qldb-dmv-sample-java/
   ```

1. 다음 명령어는 각 작업을 실행하는 Gradle 구문을 보여줍니다.

   ```
   ./gradlew run -Dtutorial=Task
   ```

   예를 들어 다음 명령을 실행하여 AWS 계정 및 현재 리전의 모든 원장을 나열합니다.

   ```
   ./gradlew run -Dtutorial=ListLedgers
   ```

1. [1단계: 새 원장 생성](getting-started.java.step-1.md)로 진행하여 자습서를 시작하고 원장을 생성하세요.

1. (선택 사항) 자습서를 완료한 후 CloudFormation 리소스가 더 이상 필요하지 않으면 정리하세요.

   1. [https://console.aws.amazon.com/cloudformation](https://console.aws.amazon.com/cloudformation/) CloudFormation 콘솔을 열고 *1부: 리소스 프로비저닝에서 생성한 스택을 삭제합니다*.

   1. 또한 CloudFormation 템플릿이 생성한 AWS Cloud9 스택을 삭제합니다.

# 1단계: 새 원장 생성
<a name="getting-started.java.step-1"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 단계에서는 `vehicle-registration`라는 이름의 새 Amazon QLDB 원장을 생성합니다

**새 원장을 생성하려면**

1. 이 자습서의 다른 모든 프로그램에서 사용하는 상수 값이 들어 있는 다음 파일(`Constants.java`)을 검토하세요.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonSystem;
   import com.amazon.ion.system.IonSystemBuilder;
   import com.fasterxml.jackson.databind.SerializationFeature;
   import com.fasterxml.jackson.dataformat.ion.IonObjectMapper;
   import com.fasterxml.jackson.dataformat.ion.ionvalue.IonValueMapper;
   
   /**
    * Constant values used throughout this tutorial.
    */
   public final class Constants {
       public static final int RETRY_LIMIT = 4;
       public static final String LEDGER_NAME = "vehicle-registration";
       public static final String STREAM_NAME = "vehicle-registration-stream";
       public static final String VEHICLE_REGISTRATION_TABLE_NAME = "VehicleRegistration";
       public static final String VEHICLE_TABLE_NAME = "Vehicle";
       public static final String PERSON_TABLE_NAME = "Person";
       public static final String DRIVERS_LICENSE_TABLE_NAME = "DriversLicense";
       public static final String VIN_INDEX_NAME = "VIN";
       public static final String PERSON_GOV_ID_INDEX_NAME = "GovId";
       public static final String VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME = "LicensePlateNumber";
       public static final String DRIVER_LICENSE_NUMBER_INDEX_NAME = "LicenseNumber";
       public static final String DRIVER_LICENSE_PERSONID_INDEX_NAME = "PersonId";
       public static final String JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX = "qldb-tutorial-journal-export";
       public static final String USER_TABLES = "information_schema.user_tables";
       public static final String LEDGER_NAME_WITH_TAGS = "tags";
       public static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
       public static final IonObjectMapper MAPPER = new IonValueMapper(SYSTEM);
   
       private Constants() { }
   
       static {
           MAPPER.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
       }
   }
   ```

------
#### [ 1.x ]

**중요**  
Amazon Ion 패키지의 경우 애플리케이션에서 네임스페이스 `com.amazon.ion`을 사용해야 합니다. 는 네임스페이스 아래의 다른 Ion 패키지에 AWS SDK for Java 종속되지만 `software.amazon.ion`QLDB 드라이버와 호환되지 않는 레거시 패키지입니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonSystem;
   import com.amazon.ion.system.IonSystemBuilder;
   import com.fasterxml.jackson.databind.SerializationFeature;
   import com.fasterxml.jackson.dataformat.ion.IonObjectMapper;
   import com.fasterxml.jackson.dataformat.ion.ionvalue.IonValueMapper;
   
   /**
    * Constant values used throughout this tutorial.
    */
   public final class Constants {
       public static final int RETRY_LIMIT = 4;
       public static final String LEDGER_NAME = "vehicle-registration";
       public static final String STREAM_NAME = "vehicle-registration-stream";
       public static final String VEHICLE_REGISTRATION_TABLE_NAME = "VehicleRegistration";
       public static final String VEHICLE_TABLE_NAME = "Vehicle";
       public static final String PERSON_TABLE_NAME = "Person";
       public static final String DRIVERS_LICENSE_TABLE_NAME = "DriversLicense";
       public static final String VIN_INDEX_NAME = "VIN";
       public static final String PERSON_GOV_ID_INDEX_NAME = "GovId";
       public static final String VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME = "LicensePlateNumber";
       public static final String DRIVER_LICENSE_NUMBER_INDEX_NAME = "LicenseNumber";
       public static final String DRIVER_LICENSE_PERSONID_INDEX_NAME = "PersonId";
       public static final String JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX = "qldb-tutorial-journal-export";
       public static final String USER_TABLES = "information_schema.user_tables";
       public static final String LEDGER_NAME_WITH_TAGS = "tags";
       public static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
       public static final IonObjectMapper MAPPER = new IonValueMapper(SYSTEM);
   
       private Constants() { }
   
       static {
           MAPPER.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
       }
   }
   ```

------
**참고**  
이 `Constants` 클래스에는 오픈 소스 Jackson `IonValueMapper` 클래스의 인스턴스가 포함되어 있습니다. 읽기 및 쓰기 트랜잭션을 수행할 때 이 매퍼를 사용하여 [Amazon Ion](ion.md) 데이터를 처리할 수 있습니다.

   또한 `CreateLedger.java` 파일은 원장의 현재 상태를 설명하는 다음 프로그램(`DescribeLedger.java`)에 대한 종속성을 가집니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.DescribeLedgerRequest;
   import com.amazonaws.services.qldb.model.DescribeLedgerResult;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Describe a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class DescribeLedger {
       public static AmazonQLDB client = CreateLedger.getClient();
       public static final Logger log = LoggerFactory.getLogger(DescribeLedger.class);
   
       private DescribeLedger() { }
   
       public static void main(final String... args) {
           try {
   
               describe(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to describe a ledger!", e);
           }
       }
   
       /**
        * Describe a ledger.
        *
        * @param name
        *              Name of the ledger to describe.
        * @return {@link DescribeLedgerResult} from QLDB.
        */
       public static DescribeLedgerResult describe(final String name) {
           log.info("Let's describe ledger with name: {}...", name);
           DescribeLedgerRequest request = new DescribeLedgerRequest().withName(name);
           DescribeLedgerResult result = client.describeLedger(request);
           log.info("Success. Ledger description: {}", result);
           return result;
       }
   }
   ```

1. `CreateLedger.java` 프로그램을 컴파일하고 실행하여 `vehicle-registration`라는 이름의 원장을 생성합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.client.builder.AwsClientBuilder;
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.AmazonQLDBClientBuilder;
   import com.amazonaws.services.qldb.model.CreateLedgerRequest;
   import com.amazonaws.services.qldb.model.CreateLedgerResult;
   import com.amazonaws.services.qldb.model.DescribeLedgerResult;
   import com.amazonaws.services.qldb.model.LedgerState;
   import com.amazonaws.services.qldb.model.PermissionsMode;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Create a ledger and wait for it to be active.
    * <p>
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateLedger {
       public static final Logger log = LoggerFactory.getLogger(CreateLedger.class);
       public static final Long LEDGER_CREATION_POLL_PERIOD_MS = 10_000L;
       public static String endpoint = null;
       public static String region = null;
       public static AmazonQLDB client = getClient();
   
       private CreateLedger() {
       }
   
       /**
        * Build a low-level QLDB client.
        *
        * @return {@link AmazonQLDB} control plane client.
        */
       public static AmazonQLDB getClient() {
           AmazonQLDBClientBuilder builder = AmazonQLDBClientBuilder.standard();
           if (null != endpoint && null != region) {
               builder.setEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(endpoint, region));
           }
           return builder.build();
       }
   
       public static void main(final String... args) throws Exception {
           try {
               client = getClient();
   
               create(Constants.LEDGER_NAME);
   
               waitForActive(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to create the ledger!", e);
               throw e;
           }
       }
   
       /**
        * Create a new ledger with the specified ledger name.
        *
        * @param ledgerName Name of the ledger to be created.
        * @return {@link CreateLedgerResult} from QLDB.
        */
       public static CreateLedgerResult create(final String ledgerName) {
           log.info("Let's create the ledger with name: {}...", ledgerName);
           CreateLedgerRequest request = new CreateLedgerRequest()
                   .withName(ledgerName)
                   .withPermissionsMode(PermissionsMode.ALLOW_ALL);
           CreateLedgerResult result = client.createLedger(request);
           log.info("Success. Ledger state: {}.", result.getState());
           return result;
       }
   
       /**
        * Wait for a newly created ledger to become active.
        *
        * @param ledgerName Name of the ledger to wait on.
        * @return {@link DescribeLedgerResult} from QLDB.
        * @throws InterruptedException if thread is being interrupted.
        */
       public static DescribeLedgerResult waitForActive(final String ledgerName) throws InterruptedException {
           log.info("Waiting for ledger to become active...");
           while (true) {
               DescribeLedgerResult result = DescribeLedger.describe(ledgerName);
               if (result.getState().equals(LedgerState.ACTIVE.name())) {
                   log.info("Success. Ledger is active and ready to use.");
                   return result;
               }
               log.info("The ledger is still creating. Please wait...");
               Thread.sleep(LEDGER_CREATION_POLL_PERIOD_MS);
           }
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.AmazonQLDBClientBuilder;
   import com.amazonaws.services.qldb.model.CreateLedgerRequest;
   import com.amazonaws.services.qldb.model.CreateLedgerResult;
   import com.amazonaws.services.qldb.model.DescribeLedgerResult;
   import com.amazonaws.services.qldb.model.LedgerState;
   import com.amazonaws.services.qldb.model.PermissionsMode;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Create a ledger and wait for it to be active.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateLedger {
       public static final Logger log = LoggerFactory.getLogger(CreateLedger.class);
       public static final Long LEDGER_CREATION_POLL_PERIOD_MS = 10_000L;
       public static AmazonQLDB client = getClient();
   
       private CreateLedger() { }
   
       /**
        * Build a low-level QLDB client.
        *
        * @return {@link AmazonQLDB} control plane client.
        */
       public static AmazonQLDB getClient() {
           return AmazonQLDBClientBuilder.standard().build();
       }
   
       public static void main(final String... args) throws Exception {
           try {
   
               create(Constants.LEDGER_NAME);
   
               waitForActive(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to create the ledger!", e);
               throw e;
           }
       }
   
       /**
        * Create a new ledger with the specified ledger name.
        *
        * @param ledgerName
        *              Name of the ledger to be created.
        * @return {@link CreateLedgerResult} from QLDB.
        */
       public static CreateLedgerResult create(final String ledgerName) {
           log.info("Let's create the ledger with name: {}...", ledgerName);
           CreateLedgerRequest request = new CreateLedgerRequest()
                   .withName(ledgerName)
                   .withPermissionsMode(PermissionsMode.ALLOW_ALL);
           CreateLedgerResult result = client.createLedger(request);
           log.info("Success. Ledger state: {}.", result.getState());
           return result;
       }
   
       /**
        * Wait for a newly created ledger to become active.
        *
        * @param ledgerName
        *              Name of the ledger to wait on.
        * @return {@link DescribeLedgerResult} from QLDB.
        * @throws InterruptedException if thread is being interrupted.
        */
       public static DescribeLedgerResult waitForActive(final String ledgerName) throws InterruptedException {
           log.info("Waiting for ledger to become active...");
           while (true) {
               DescribeLedgerResult result = DescribeLedger.describe(ledgerName);
               if (result.getState().equals(LedgerState.ACTIVE.name())) {
                   log.info("Success. Ledger is active and ready to use.");
                   return result;
               }
               log.info("The ledger is still creating. Please wait...");
               Thread.sleep(LEDGER_CREATION_POLL_PERIOD_MS);
           }
       }
   }
   ```

------
**참고**  
`createLedger` 호출 시 원장 이름과 권한 모드를 지정해야 합니다. 원장 데이터의 보안을 극대화하려면 `STANDARD` 권한 모드를 사용할 것을 권장합니다.
원장을 생성할 때 기본적으로 *삭제 방지*가 활성화됩니다. 이 기능은 사용자가 원장을 삭제하는 것을 방지하는 QLDB의 기능입니다. QLDB API 또는 AWS Command Line Interface ()를 사용하여 원장 생성 시 삭제 방지 기능을 비활성화할 수 있습니다AWS CLI.
선택적으로, 원장에 첨부할 태그를 지정할 수도 있습니다.

새 원장과의 연결을 확인하려면 [2단계: 원장과의 연결을 테스트](getting-started.java.step-2.md)로 이동하세요.

# 2단계: 원장과의 연결을 테스트
<a name="getting-started.java.step-2"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 단계에서는 트랜잭션 데이터 API 엔드포인트를 사용하여 Amazon QLDB의 `vehicle-registration` 원장에 연결할 수 있는지 확인합니다.

**원장과의 연결을 테스트하려면**

1. `vehicle-registration` 원장에 대한 데이터 세션 연결을 생성하는 다음 프로그램(`ConnectToLedger.java`)을 검토합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.net.URI;
   import java.net.URISyntaxException;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.awssdk.auth.credentials.AwsCredentialsProvider;
   import software.amazon.awssdk.services.qldbsession.QldbSessionClient;
   import software.amazon.awssdk.services.qldbsession.QldbSessionClientBuilder;
   import software.amazon.qldb.QldbDriver;
   import software.amazon.qldb.RetryPolicy;
   
   /**
    * Connect to a session for a given ledger using default settings.
    * <p>
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class ConnectToLedger {
       public static final Logger log = LoggerFactory.getLogger(ConnectToLedger.class);
       public static AwsCredentialsProvider credentialsProvider;
       public static String endpoint = null;
       public static String ledgerName = Constants.LEDGER_NAME;
       public static String region = null;
       public static QldbDriver driver;
   
       private ConnectToLedger() {
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @param retryAttempts How many times the transaction will be retried in
        * case of a retryable issue happens like Optimistic Concurrency Control exception,
        * server side failures or network issues.
        * @return The pooled driver for creating sessions.
        */
       public static QldbDriver createQldbDriver(int retryAttempts) {
           QldbSessionClientBuilder builder = getAmazonQldbSessionClientBuilder();
           return QldbDriver.builder()
                                .ledger(ledgerName)
                                .transactionRetryPolicy(RetryPolicy
                                      .builder()
                                      .maxRetries(retryAttempts)
                                      .build())
                                .sessionClientBuilder(builder)
                                .build();
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static QldbDriver createQldbDriver() {
           QldbSessionClientBuilder builder = getAmazonQldbSessionClientBuilder();
           return QldbDriver.builder()
               .ledger(ledgerName)
               .transactionRetryPolicy(RetryPolicy.builder()
                                                  .maxRetries(Constants.RETRY_LIMIT).build())
               .sessionClientBuilder(builder)
               .build();
       }
   
       /**
        * Creates a QldbSession builder that is passed to the QldbDriver to connect to the Ledger.
        *
        * @return An instance of the AmazonQLDBSessionClientBuilder
        */
       public static QldbSessionClientBuilder getAmazonQldbSessionClientBuilder() {
           QldbSessionClientBuilder builder = QldbSessionClient.builder();
           if (null != endpoint && null != region) {
               try {
                   builder.endpointOverride(new URI(endpoint));
               } catch (URISyntaxException e) {
                   throw new IllegalArgumentException(e);
               }
           }
           if (null != credentialsProvider) {
               builder.credentialsProvider(credentialsProvider);
           }
           return builder;
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static QldbDriver getDriver() {
           if (driver == null) {
               driver = createQldbDriver();
           }
           return driver;
       }
   
   
       public static void main(final String... args) {
           Iterable<String> tables = ConnectToLedger.getDriver().getTableNames();
           log.info("Existing tables in the ledger:");
           for (String table : tables) {
               log.info("- {} ", table);
           }
       }
   }
   ```

**참고**  
원장에서 데이터 작업을 실행하려면 특정 원장에 연결할 `QldbDriver` 클래스 인스턴스를 생성해야 합니다. 이는 이전 단계에서 원장을 생성할 때 사용한 `AmazonQLDB` 클라이언트와는 다른 클라이언트 객체입니다. 이전 클라이언트는 [Amazon QLDB API 참조](api-reference.md)에 나열된 관리 API 작업을 실행하는 데만 사용됩니다.
먼저 `QldbDriver` 객체를 생성해야 합니다. 이 드라이버를 생성할 때 원장 이름을 지정해야 합니다.  
그런 다음 이 드라이버의 `execute` 메서드를 사용하여 PartiQL 명령문을 실행할 수 있습니다.
선택적으로 트랜잭션 예외에 대한 최대 재시도 횟수를 지정할 수 있습니다. 이 `execute` 메서드는 OCC(낙관적 동시성 제어) 충돌 및 기타 일반적인 일시적 예외를 이 구성 가능한 한도까지 자동으로 재시도합니다. 기본값은 `4`입니다.  
한도에 도달한 후에도 트랜잭션이 여전히 실패하면 드라이버에서 예외가 발생합니다. 자세한 내용은 [Amazon QLDB의 드라이버를 사용한 재시도 정책에 대한 이해](driver-retry-policy.md)을 참조하십시오.

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.auth.AWSCredentialsProvider;
   import com.amazonaws.client.builder.AwsClientBuilder;
   import com.amazonaws.services.qldbsession.AmazonQLDBSessionClientBuilder;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.PooledQldbDriver;
   import software.amazon.qldb.QldbDriver;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.exceptions.QldbClientException;
   
   /**
    * Connect to a session for a given ledger using default settings.
    * <p>
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class ConnectToLedger {
       public static final Logger log = LoggerFactory.getLogger(ConnectToLedger.class);
       public static AWSCredentialsProvider credentialsProvider;
       public static String endpoint = null;
       public static String ledgerName = Constants.LEDGER_NAME;
       public static String region = null;
       private static PooledQldbDriver driver;
   
       private ConnectToLedger() {
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static PooledQldbDriver createQldbDriver() {
           AmazonQLDBSessionClientBuilder builder = AmazonQLDBSessionClientBuilder.standard();
           if (null != endpoint && null != region) {
               builder.setEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(endpoint, region));
           }
           if (null != credentialsProvider) {
               builder.setCredentials(credentialsProvider);
           }
           return PooledQldbDriver.builder()
                   .withLedger(ledgerName)
                   .withRetryLimit(Constants.RETRY_LIMIT)
                   .withSessionClientBuilder(builder)
                   .build();
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static PooledQldbDriver getDriver() {
           if (driver == null) {
               driver = createQldbDriver();
           }
           return driver;
       }
   
       /**
        * Connect to a ledger through a {@link QldbDriver}.
        *
        * @return {@link QldbSession}.
        */
       public static QldbSession createQldbSession() {
           return getDriver().getSession();
       }
   
       public static void main(final String... args) {
           try (QldbSession qldbSession = createQldbSession()) {
               log.info("Listing table names ");
               for (String tableName : qldbSession.getTableNames()) {
                   log.info(tableName);
               }
           } catch (QldbClientException e) {
               log.error("Unable to create session.", e);
           }
       }
   }
   ```

**참고**  
원장에서 데이터 작업을 실행하려면 특정 원장에 연결할 `PooledQldbDriver` 또는 `QldbDriver` 클래스 인스턴스를 생성해야 합니다. 이는 이전 단계에서 원장을 생성할 때 사용한 `AmazonQLDB` 클라이언트와는 다른 클라이언트 객체입니다. 이전 클라이언트는 [Amazon QLDB API 참조](api-reference.md)에 나열된 관리 API 작업을 실행하는 데만 사용됩니다.  
`QldbDriver`로 사용자 지정 세션 풀을 구현해야 하는 경우가 아니라면 `PooledQldbDriver`를 사용하는 것이 좋습니다. `PooledQldbDriver`의 기본 풀 크기는 세션 클라이언트가 허용하는 [최대 열린 HTTP 연결 수](https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/ClientConfiguration.html#getMaxConnections--)입니다.
먼저 `PooledQldbDriver` 객체를 생성해야 합니다. 이 드라이버를 생성할 때 원장 이름을 지정해야 합니다.  
그런 다음 이 드라이버의 `execute` 메서드를 사용하여 PartiQL 명령문을 실행할 수 있습니다. 또는 이 풀링된 드라이버 객체에서 세션을 수동으로 만들고 세션의 `execute` 메서드를 사용할 수 있습니다. 세션은 원장과의 단일 연결을 나타냅니다.
선택적으로 트랜잭션 예외에 대한 최대 재시도 횟수를 지정할 수 있습니다. 이 `execute` 메서드는 OCC(낙관적 동시성 제어) 충돌 및 기타 일반적인 일시적 예외를 이 구성 가능한 한도까지 자동으로 재시도합니다. 기본값은 `4`입니다.  
한도에 도달한 후에도 트랜잭션이 여전히 실패하면 드라이버에서 예외가 발생합니다. 자세한 내용은 [Amazon QLDB의 드라이버를 사용한 재시도 정책에 대한 이해](driver-retry-policy.md)을 참조하십시오.

------

1. `ConnectToLedger.java` 프로그램을 컴파일하고 실행하여 `vehicle-registration` 원장에 대한 데이터 세션 연결을 테스트하세요.

**재정의 AWS 리전**

샘플 애플리케이션은 기본값의 QLDB에 연결되며 AWS 리전, 사전 조건 단계에 설명된 대로 설정할 수 있습니다[기본 AWS 보안 인증 정보 및 리전 설정](getting-started.java.md#getting-started.java.credentials). 또한 QLDB 세션 클라이언트 빌더 속성을 수정하여 리전을 변경할 수 있습니다.

------
#### [ 2.x ]

다음 코드 예제에서는 새 `QldbSessionClientBuilder` 객체를 인스턴스화합니다.

```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.qldbsession.QldbSessionClientBuilder;

// This client builder will default to US East (Ohio)
QldbSessionClientBuilder builder = QldbSessionClient.builder()
    .region(Region.US_EAST_2);
```

`region` 메서드를 사용하면 사용할 수 있는 어떤 리전의 QLDB에 대해서도 코드를 실행할 수 있습니다. 전체 목록은 *AWS 일반 참조*에서 [Amazon QLDB 엔드포인트 및 할당량](https://docs.aws.amazon.com/general/latest/gr/qldb.html)을 참조하세요.

------
#### [ 1.x ]

다음 코드 예제에서는 새 `AmazonQLDBSessionClientBuilder` 객체를 인스턴스화합니다.

```
import com.amazonaws.regions.Regions;
import com.amazonaws.services.qldbsession.AmazonQLDBSessionClientBuilder;

// This client builder will default to US East (Ohio)
AmazonQLDBSessionClientBuilder builder = AmazonQLDBSessionClientBuilder.standard()
    .withRegion(Regions.US_EAST_2);
```

`withRegion` 메서드를 사용하면 사용할 수 있는 어떤 리전의 QLDB에 대해서도 코드를 실행할 수 있습니다. 전체 목록은 *AWS 일반 참조*에서 [Amazon QLDB 엔드포인트 및 할당량](https://docs.aws.amazon.com/general/latest/gr/qldb.html)을 참조하세요.

------

`vehicle-registration` 원장에 테이블을 생성하려면 [3단계: 테이블, 인덱스 및 샘플 데이터 생성](getting-started.java.step-3.md)로 진행하세요.

# 3단계: 테이블, 인덱스 및 샘플 데이터 생성
<a name="getting-started.java.step-3"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB 원장이 활성화되고 연결을 수락하면 차량, 소유자 및 등록 정보에 대한 데이터 테이블 생성을 시작할 수 있습니다. 테이블과 인덱스를 생성한 후 데이터를 로드할 수 있습니다.

이 단계에서는 `vehicle-registration` 원장에 4개의 테이블을 생성합니다.
+ `VehicleRegistration`
+ `Vehicle`
+ `Person`
+ `DriversLicense`

또한 다음과 같은 인덱스를 생성합니다.


****  

| 테이블 이름 | 필드 | 
| --- | --- | 
| VehicleRegistration | VIN | 
| VehicleRegistration | LicensePlateNumber | 
| Vehicle | VIN | 
| Person | GovId | 
| DriversLicense | LicenseNumber | 
| DriversLicense | PersonId | 

샘플 데이터를 삽입할 때는 먼저 `Person` 테이블에 문서를 삽입합니다. 그런 다음 각 `Person` 문서에서 시스템이 할당한 `id`를 사용하여 적절한 `VehicleRegistration` 및 `DriversLicense` 문서의 해당 필드를 채웁니다.

**작은 정보**  
가장 좋은 방법은 문서의 시스템 할당 `id`를 외래 키로 사용하는 것입니다. 고유 식별자(예: 차량의 VIN)로 사용되는 필드를 정의할 수 있지만 문서의 실제  고유 식별자는 `id`입니다. 이 필드는 문서의 메타데이터에 포함되며 *커밋된 뷰*(테이블의 시스텀 정의 뷰)에서 쿼리할 수 있습니다.  
QLDB 뷰에 대한 자세한 내용은 [핵심 개념](ledger-structure.md) 섹션을 참조하세요. 메타데이터에 대해 자세히 알아보려면 [문서 메타데이터 쿼리](working.metadata.md) 섹션을 참조하세요.

**샘플 데이터를 설정하려면**

1. 다음 `.java` 파일을 검토합니다. 이러한 모델 클래스는 `vehicle-registration` 테이블에 저장하는 문서를 나타냅니다. Amazon Ion 형식으로 또는 Amazon Ion 형식에서 직렬화할 수 있습니다.
**참고**  
[Amazon QLDB 문서](ql-reference.docs.md)는 JSON의 상위 집합인 Ion 형식으로 저장됩니다. 따라서 FasterXML Jackson 라이브러리를 사용하여 데이터를 JSON으로 모델링할 수 있습니다.

   1. `DriversLicense.java`

      ```
      /*
       * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      import java.time.LocalDate;
      
      /**
       * Represents a driver's license, serializable to (and from) Ion.
       */
      public final class DriversLicense implements RevisionData {
          private final String personId;
          private final String licenseNumber;
          private final String licenseType;
      
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          private final LocalDate validFromDate;
      
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          private final LocalDate validToDate;
      
          @JsonCreator
          public DriversLicense(@JsonProperty("PersonId") final String personId,
                                @JsonProperty("LicenseNumber") final String licenseNumber,
                                @JsonProperty("LicenseType") final String licenseType,
                                @JsonProperty("ValidFromDate") final LocalDate validFromDate,
                                @JsonProperty("ValidToDate") final LocalDate validToDate) {
              this.personId = personId;
              this.licenseNumber = licenseNumber;
              this.licenseType = licenseType;
              this.validFromDate = validFromDate;
              this.validToDate = validToDate;
          }
      
          @JsonProperty("PersonId")
          public String getPersonId() {
              return personId;
          }
      
          @JsonProperty("LicenseNumber")
          public String getLicenseNumber() {
              return licenseNumber;
          }
      
          @JsonProperty("LicenseType")
          public String getLicenseType() {
              return licenseType;
          }
      
          @JsonProperty("ValidFromDate")
          public LocalDate getValidFromDate() {
              return  validFromDate;
          }
      
          @JsonProperty("ValidToDate")
          public LocalDate getValidToDate() {
              return  validToDate;
          }
      
          @Override
          public String toString() {
              return "DriversLicense{" +
                      "personId='" + personId + '\'' +
                      ", licenseNumber='" + licenseNumber + '\'' +
                      ", licenseType='" + licenseType + '\'' +
                      ", validFromDate=" + validFromDate +
                      ", validToDate=" + validToDate +
                      '}';
          }
      }
      ```

   1. `Person.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import java.time.LocalDate;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      
      import software.amazon.qldb.TransactionExecutor;
      import software.amazon.qldb.tutorial.Constants;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      /**
       * Represents a person, serializable to (and from) Ion.
       */ 
      public final class Person implements RevisionData {
          private final String firstName;
          private final String lastName;
      
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          private final LocalDate dob;
          private final String govId;
          private final String govIdType;
          private final String address;
      
          @JsonCreator
          public Person(@JsonProperty("FirstName") final String firstName,
                        @JsonProperty("LastName") final String lastName,
                        @JsonProperty("DOB") final LocalDate dob,
                        @JsonProperty("GovId") final String govId,
                        @JsonProperty("GovIdType") final String govIdType,
                        @JsonProperty("Address") final String address) {
              this.firstName = firstName;
              this.lastName = lastName;
              this.dob = dob;
              this.govId = govId;
              this.govIdType = govIdType;
              this.address = address;
          }
      
          @JsonProperty("Address")
          public String getAddress() {
              return address;
          }
      
          @JsonProperty("DOB")
          public LocalDate getDob() {
              return dob;
          }
      
          @JsonProperty("FirstName")
          public String getFirstName() {
              return firstName;
          }
      
          @JsonProperty("LastName")
          public String getLastName() {
              return lastName;
          }
      
          @JsonProperty("GovId")
          public String getGovId() {
              return govId;
          }
      
          @JsonProperty("GovIdType")
          public String getGovIdType() {
              return govIdType;
          }
      
          /**
           * This returns the unique document ID given a specific government ID.
           *
           * @param txn
           *              A transaction executor object.
           * @param govId
           *              The government ID of a driver.
           * @return the unique document ID.
           */
          public static String getDocumentIdByGovId(final TransactionExecutor txn, final String govId) {
              return SampleData.getDocumentId(txn, Constants.PERSON_TABLE_NAME, "GovId", govId);
          }
      
          @Override
          public String toString() {
              return "Person{" +
                      "firstName='" + firstName + '\'' +
                      ", lastName='" + lastName + '\'' +
                      ", dob=" + dob +
                      ", govId='" + govId + '\'' +
                      ", govIdType='" + govIdType + '\'' +
                      ", address='" + address + '\'' +
                      '}';
          }
      }
      ```

   1. `VehicleRegistration.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      import software.amazon.qldb.TransactionExecutor;
      import software.amazon.qldb.tutorial.Constants;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      import java.math.BigDecimal;
      import java.time.LocalDate;
      
      /**
       * Represents a vehicle registration, serializable to (and from) Ion.
       */ 
      public final class VehicleRegistration implements RevisionData {
      
          private final String vin;
          private final String licensePlateNumber;
          private final String state;
          private final String city;
          private final BigDecimal pendingPenaltyTicketAmount;
          private final LocalDate validFromDate;
          private final LocalDate validToDate;
          private final Owners owners;
      
          @JsonCreator
          public VehicleRegistration(@JsonProperty("VIN") final String vin,
                                     @JsonProperty("LicensePlateNumber") final String licensePlateNumber,
                                     @JsonProperty("State") final String state,
                                     @JsonProperty("City") final String city,
                                     @JsonProperty("PendingPenaltyTicketAmount") final BigDecimal pendingPenaltyTicketAmount,
                                     @JsonProperty("ValidFromDate") final LocalDate validFromDate,
                                     @JsonProperty("ValidToDate") final LocalDate validToDate,
                                     @JsonProperty("Owners") final Owners owners) {
              this.vin = vin;
              this.licensePlateNumber = licensePlateNumber;
              this.state = state;
              this.city = city;
              this.pendingPenaltyTicketAmount = pendingPenaltyTicketAmount;
              this.validFromDate = validFromDate;
              this.validToDate = validToDate;
              this.owners = owners;
          }
      
          @JsonProperty("City")
          public String getCity() {
              return city;
          }
      
          @JsonProperty("LicensePlateNumber")
          public String getLicensePlateNumber() {
              return licensePlateNumber;
          }
      
          @JsonProperty("Owners")
          public Owners getOwners() {
              return owners;
          }
      
          @JsonProperty("PendingPenaltyTicketAmount")
          public BigDecimal getPendingPenaltyTicketAmount() {
              return pendingPenaltyTicketAmount;
          }
      
          @JsonProperty("State")
          public String getState() {
              return state;
          }
      
          @JsonProperty("ValidFromDate")
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          public LocalDate getValidFromDate() {
              return validFromDate;
          }
      
          @JsonProperty("ValidToDate")
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          public LocalDate getValidToDate() {
              return validToDate;
          }
      
          @JsonProperty("VIN")
          public String getVin() {
              return vin;
          }
      
          /**
           * Returns the unique document ID of a vehicle given a specific VIN.
           *
           * @param txn
           *              A transaction executor object.
           * @param vin
           *              The VIN of a vehicle.
           * @return the unique document ID of the specified vehicle.
           */
          public static String getDocumentIdByVin(final TransactionExecutor txn, final String vin) {
              return SampleData.getDocumentId(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME, "VIN", vin);
          }
      
          @Override
          public String toString() {
              return "VehicleRegistration{" +
                      "vin='" + vin + '\'' +
                      ", licensePlateNumber='" + licensePlateNumber + '\'' +
                      ", state='" + state + '\'' +
                      ", city='" + city + '\'' +
                      ", pendingPenaltyTicketAmount=" + pendingPenaltyTicketAmount +
                      ", validFromDate=" + validFromDate +
                      ", validToDate=" + validToDate +
                      ", owners=" + owners +
                      '}';
          }
      }
      ```

   1. `Vehicle.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      /**
       * Represents a vehicle, serializable to (and from) Ion.
       */
      public final class Vehicle implements RevisionData {
          private final String vin;
          private final String type;
          private final int year;
          private final String make;
          private final String model;
          private final String color;
      
          @JsonCreator
          public Vehicle(@JsonProperty("VIN") final String vin,
                         @JsonProperty("Type") final String type,
                         @JsonProperty("Year") final int year,
                         @JsonProperty("Make") final String make,
                         @JsonProperty("Model") final String model,
                         @JsonProperty("Color") final String color) {
              this.vin = vin;
              this.type = type;
              this.year = year;
              this.make = make;
              this.model = model;
              this.color = color;
          }
      
          @JsonProperty("Color")
          public String getColor() {
              return color;
          }
      
          @JsonProperty("Make")
          public String getMake() {
              return make;
          }
      
          @JsonProperty("Model")
          public String getModel() {
              return model;
          }
      
          @JsonProperty("Type")
          public String getType() {
              return type;
          }
      
          @JsonProperty("VIN")
          public String getVin() {
              return vin;
          }
      
          @JsonProperty("Year")
          public int getYear() {
              return year;
          }
      
          @Override
          public String toString() {
              return "Vehicle{" +
                      "vin='" + vin + '\'' +
                      ", type='" + type + '\'' +
                      ", year=" + year +
                      ", make='" + make + '\'' +
                      ", model='" + model + '\'' +
                      ", color='" + color + '\'' +
                      '}';
          }
      }
      ```

   1. `Owner.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      /**
       * Represents a vehicle owner, serializable to (and from) Ion.
       */ 
      public final class Owner {
          private final String personId;
      
          public Owner(@JsonProperty("PersonId") final String personId) {
              this.personId = personId;
          }
      
          @JsonProperty("PersonId")
          public String getPersonId() {
              return personId;
          }
      
          @Override
          public String toString() {
              return "Owner{" +
                      "personId='" + personId + '\'' +
                      '}';
          }
      }
      ```

   1. `Owners.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      import java.util.List;
      
      /**
       * Represents a set of owners for a given vehicle, serializable to (and from) Ion.
       */ 
      public final class Owners {
          private final Owner primaryOwner;
          private final List<Owner> secondaryOwners;
      
          public Owners(@JsonProperty("PrimaryOwner") final Owner primaryOwner,
                        @JsonProperty("SecondaryOwners") final List<Owner> secondaryOwners) {
              this.primaryOwner = primaryOwner;
              this.secondaryOwners = secondaryOwners;
          }
      
          @JsonProperty("PrimaryOwner")
          public Owner getPrimaryOwner() {
              return primaryOwner;
          }
      
          @JsonProperty("SecondaryOwners")
          public List<Owner> getSecondaryOwners() {
              return secondaryOwners;
          }
      
          @Override
          public String toString() {
              return "Owners{" +
                      "primaryOwner=" + primaryOwner +
                      ", secondaryOwners=" + secondaryOwners +
                      '}';
          }
      }
      ```

   1. `DmlResultDocument.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      /**
       * Contains information about an individual document inserted or modified
       * as a result of DML.
       */
      public class DmlResultDocument {
      
          private String documentId;
      
          @JsonCreator
          public DmlResultDocument(@JsonProperty("documentId") final String documentId) {
              this.documentId = documentId;
          }
      
          public String getDocumentId() {
              return documentId;
          }
      
          @Override
          public String toString() {
              return "DmlResultDocument{"
                  + "documentId='" + documentId + '\''
                  + '}';
          }
      }
      ```

   1. `RevisionData.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model.streams;
      
      /**
       * Allows modeling the content of all revisions as a generic revision data. Used
       * in the {@link Revision} and extended by domain models in {@link
       * software.amazon.qldb.tutorial.model} to make it easier to write the {@link
       * Revision.RevisionDataDeserializer} that must deserialize the {@link
       * Revision#data} from different domain models.
       */
      public interface RevisionData { }
      ```

   1. `RevisionMetadata.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonInt;
      import com.amazon.ion.IonString;
      import com.amazon.ion.IonStruct;
      import com.amazon.ion.IonTimestamp;
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      import com.fasterxml.jackson.dataformat.ion.IonTimestampSerializers;
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      
      import java.util.Date;
      import java.util.Objects;
      
      /**
       * Represents the metadata field of a QLDB Document
       */
      public class RevisionMetadata {
          private static final Logger log = LoggerFactory.getLogger(RevisionMetadata.class);
          private final String id;
          private final long version;
          @JsonSerialize(using = IonTimestampSerializers.IonTimestampJavaDateSerializer.class)
          private final Date txTime;
          private final String txId;
      
          @JsonCreator
          public RevisionMetadata(@JsonProperty("id") final String id,
                                  @JsonProperty("version") final long version,
                                  @JsonProperty("txTime") final Date txTime,
                                  @JsonProperty("txId") final String txId) {
              this.id = id;
              this.version = version;
              this.txTime = txTime;
              this.txId = txId;
          }
      
          /**
           * Gets the unique ID of a QLDB document.
           *
           * @return the document ID.
           */
          public String getId() {
              return id;
          }
      
          /**
           * Gets the version number of the document in the document's modification history.
           * @return the version number.
           */
          public long getVersion() {
              return version;
          }
      
          /**
           * Gets the time during which the document was modified.
           *
           * @return the transaction time.
           */
          public Date getTxTime() {
              return txTime;
          }
      
          /**
           * Gets the transaction ID associated with this document.
           *
           * @return the transaction ID.
           */
          public String getTxId() {
              return txId;
          }
      
          public static RevisionMetadata fromIon(final IonStruct ionStruct) {
              if (ionStruct == null) {
                  throw new IllegalArgumentException("Metadata cannot be null");
              }
              try {
                  IonString id = (IonString) ionStruct.get("id");
                  IonInt version = (IonInt) ionStruct.get("version");
                  IonTimestamp txTime = (IonTimestamp) ionStruct.get("txTime");
                  IonString txId = (IonString) ionStruct.get("txId");
                  if (id == null || version == null || txTime == null || txId == null) {
                      throw new IllegalArgumentException("Document is missing required fields");
                  }
                  return new RevisionMetadata(id.stringValue(), version.longValue(), new Date(txTime.getMillis()), txId.stringValue());
              } catch (ClassCastException e) {
                  log.error("Failed to parse ion document");
                  throw new IllegalArgumentException("Document members are not of the correct type", e);
              }
          }
      
          /**
           * Converts a {@link RevisionMetadata} object to a string.
           *
           * @return the string representation of the {@link QldbRevision} object.
           */
          @Override
          public String toString() {
              return "Metadata{"
                      + "id='" + id + '\''
                      + ", version=" + version
                      + ", txTime=" + txTime
                      + ", txId='" + txId
                      + '\''
                      + '}';
          }
      
          /**
           * Check whether two {@link RevisionMetadata} objects are equivalent.
           *
           * @return {@code true} if the two objects are equal, {@code false} otherwise.
           */
          @Override
          public boolean equals(Object o) {
              if (this == o) { return true; }
              if (o == null || getClass() != o.getClass()) { return false; }
              RevisionMetadata metadata = (RevisionMetadata) o;
              return version == metadata.version
                      && id.equals(metadata.id)
                      && txTime.equals(metadata.txTime)
                      && txId.equals(metadata.txId);
          }
      
          /**
           * Generate a hash code for the {@link RevisionMetadata} object.
           *
           * @return the hash code.
           */
          @Override
          public int hashCode() {
              // CHECKSTYLE:OFF - Disabling as we are generating a hashCode of multiple properties.
              return Objects.hash(id, version, txTime, txId);
              // CHECKSTYLE:ON
          }
      }
      ```

   1. `QldbRevision.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonBlob;
      import com.amazon.ion.IonStruct;
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      import software.amazon.qldb.tutorial.Constants;
      import software.amazon.qldb.tutorial.Verifier;
      
      import java.io.IOException;
      import java.util.Arrays;
      import java.util.Objects;
      
      /**
       * Represents a QldbRevision including both user data and metadata.
       */
      public final class QldbRevision {
          private static final Logger log = LoggerFactory.getLogger(QldbRevision.class);
      
          private final BlockAddress blockAddress;
          private final RevisionMetadata metadata;
          private final byte[] hash;
          private final byte[] dataHash;
          private final IonStruct data;
      
          @JsonCreator
          public QldbRevision(@JsonProperty("blockAddress") final BlockAddress blockAddress,
                              @JsonProperty("metadata") final RevisionMetadata metadata,
                              @JsonProperty("hash") final byte[] hash,
                              @JsonProperty("dataHash") final byte[] dataHash,
                              @JsonProperty("data") final IonStruct data) {
              this.blockAddress = blockAddress;
              this.metadata = metadata;
              this.hash = hash;
              this.dataHash = dataHash;
              this.data = data;
          }
      
          /**
           * Gets the unique ID of a QLDB document.
           *
           * @return the {@link BlockAddress} object.
           */
          public BlockAddress getBlockAddress() {
              return blockAddress;
          }
      
          /**
           * Gets the metadata of the revision.
           *
           * @return the {@link RevisionMetadata} object.
           */
          public RevisionMetadata getMetadata() {
              return metadata;
          }
      
          /**
           * Gets the SHA-256 hash value of the revision.
           * This is equivalent to the hash of the revision metadata and data.
           *
           * @return the byte array representing the hash.
           */
          public byte[] getHash() {
              return hash;
          }
      
          /**
           * Gets the SHA-256 hash value of the data portion of the revision.
           * This is only present if the revision is redacted.
           *
           * @return the byte array representing the hash.
           */
          public byte[] getDataHash() {
              return dataHash;
          }
      
          /**
           * Gets the revision data.
           *
           * @return the revision data.
           */
          public IonStruct getData() {
              return data;
          }
      
          /**
           * Returns true if the revision has been redacted.
           * @return a boolean value representing the redaction status
           * of this revision.
           */
          public Boolean isRedacted() {
              return dataHash != null;
          }
      
          /**
           * Constructs a new {@link QldbRevision} from an {@link IonStruct}.
           *
           * The specified {@link IonStruct} must include the following fields
           *
           * - blockAddress -- a {@link BlockAddress},
           * - metadata -- a {@link RevisionMetadata},
           * - hash -- the revision's hash calculated by QLDB,
           * - dataHash -- the user data's hash calculated by QLDB (only present if revision is redacted),
           * - data -- an {@link IonStruct} containing user data in the document.
           *
           * If any of these fields are missing or are malformed, then throws {@link IllegalArgumentException}.
           *
           * If the document hash calculated from the members of the specified {@link IonStruct} does not match
           * the hash member of the {@link IonStruct} then throws {@link IllegalArgumentException}.
           *
           * @param ionStruct
           *              The {@link IonStruct} that contains a {@link QldbRevision} object.
           * @return the converted {@link QldbRevision} object.
           * @throws IOException if failed to parse parameter {@link IonStruct}.
           */
          public static QldbRevision fromIon(final IonStruct ionStruct) throws IOException {
              try {
                  BlockAddress blockAddress = Constants.MAPPER.readValue(ionStruct.get("blockAddress"), BlockAddress.class);
                  IonBlob revisionHash = (IonBlob) ionStruct.get("hash");
                  IonStruct metadataStruct = (IonStruct) ionStruct.get("metadata");
                  IonStruct data = ionStruct.get("data") == null || ionStruct.get("data").isNullValue() ?
                      null : (IonStruct) ionStruct.get("data");
                  IonBlob dataHash = ionStruct.get("dataHash") == null || ionStruct.get("dataHash").isNullValue() ?
                      null : (IonBlob) ionStruct.get("dataHash");
                  if (revisionHash == null || metadataStruct == null) {
                      throw new IllegalArgumentException("Document is missing required fields");
                  }
                  byte[] dataHashBytes = dataHash != null ? dataHash.getBytes() : QldbIonUtils.hashIonValue(data);
                  verifyRevisionHash(metadataStruct, dataHashBytes, revisionHash.getBytes());
                  RevisionMetadata metadata = RevisionMetadata.fromIon(metadataStruct);
                  return new QldbRevision(
                          blockAddress,
                          metadata,
                          revisionHash.getBytes(),
                          dataHash != null ? dataHash.getBytes() : null,
                          data
                  );
              } catch (ClassCastException e) {
                  log.error("Failed to parse ion document");
                  throw new IllegalArgumentException("Document members are not of the correct type", e);
              }
          }
      
          /**
           * Converts a {@link QldbRevision} object to string.
           *
           * @return the string representation of the {@link QldbRevision} object.
           */
          @Override
          public String toString() {
              return "QldbRevision{" +
                      "blockAddress=" + blockAddress +
                      ", metadata=" + metadata +
                      ", hash=" + Arrays.toString(hash) +
                      ", dataHash=" + Arrays.toString(dataHash) +
                      ", data=" + data +
                      '}';
          }
      
          /**
           * Check whether two {@link QldbRevision} objects are equivalent.
           *
           * @return {@code true} if the two objects are equal, {@code false} otherwise.
           */
          @Override
          public boolean equals(final Object o) {
              if (this == o) {
                  return true;
              }
              if (!(o instanceof QldbRevision)) {
                  return false;
              }
              final QldbRevision that = (QldbRevision) o;
              return Objects.equals(getBlockAddress(), that.getBlockAddress())
                      && Objects.equals(getMetadata(), that.getMetadata())
                      && Arrays.equals(getHash(), that.getHash())
                      && Arrays.equals(getDataHash(), that.getDataHash())
                      && Objects.equals(getData(), that.getData());
          }
      
          /**
           * Create a hash code for the {@link QldbRevision} object.
           *
           * @return the hash code.
           */
          @Override
          public int hashCode() {
              // CHECKSTYLE:OFF - Disabling as we are generating a hashCode of multiple properties.
              int result = Objects.hash(blockAddress, metadata, data);
              // CHECKSTYLE:ON
              result = 31 * result + Arrays.hashCode(hash);
              return result;
          }
      
          /**
           * Throws an IllegalArgumentException if the hash of the revision data and metadata
           * does not match the hash provided by QLDB with the revision.
           */
          public void verifyRevisionHash() {
              // Certain internal-only system revisions only contain a hash which cannot be
              // further computed. However, these system hashes still participate to validate
              // the journal block. User revisions will always contain values for all fields
              // and can therefore have their hash computed.
              if (blockAddress == null && metadata == null && data == null && dataHash == null) {
                  return;
              }
      
              try {
                  IonStruct metadataIon = (IonStruct) Constants.MAPPER.writeValueAsIonValue(metadata);
                  byte[] dataHashBytes = isRedacted() ? dataHash : QldbIonUtils.hashIonValue(data);
                  verifyRevisionHash(metadataIon, dataHashBytes, hash);
              } catch (IOException e) {
                  throw new IllegalArgumentException("Could not encode revision metadata to ion.", e);
              }
          }
      
          private static void verifyRevisionHash(IonStruct metadata, byte[] dataHash, byte[] expectedHash) {
              byte[] metadataHash = QldbIonUtils.hashIonValue(metadata);
              byte[] candidateHash = Verifier.dot(metadataHash, dataHash);
              if (!Arrays.equals(candidateHash, expectedHash)) {
                  throw new IllegalArgumentException("Hash entry of QLDB revision and computed hash "
                          + "of QLDB revision do not match");
              }
          }
      }
      ```

   1. `IonLocalDateDeserializer.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.amazon.ion.Timestamp;
      import com.fasterxml.jackson.core.JsonParser;
      import com.fasterxml.jackson.databind.DeserializationContext;
      import com.fasterxml.jackson.databind.JsonDeserializer;
      
      import java.io.IOException;
      import java.time.LocalDate;
      
      /**
       * Deserializes [java.time.LocalDate] from Ion.
       */
      public class IonLocalDateDeserializer extends JsonDeserializer<LocalDate> {
      
          @Override
          public LocalDate deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
              return timestampToLocalDate((Timestamp) jp.getEmbeddedObject());
          }
      
          private LocalDate timestampToLocalDate(Timestamp timestamp) {
              return LocalDate.of(timestamp.getYear(), timestamp.getMonth(), timestamp.getDay());
          }
      }
      ```

   1. `IonLocalDateSerializer.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.amazon.ion.Timestamp;
      import com.fasterxml.jackson.core.JsonGenerator;
      import com.fasterxml.jackson.databind.SerializerProvider;
      import com.fasterxml.jackson.databind.ser.std.StdScalarSerializer;
      import com.fasterxml.jackson.dataformat.ion.IonGenerator;
      
      import java.io.IOException;
      import java.time.LocalDate;
      
      /**
       * Serializes [java.time.LocalDate] to Ion.
       */
      public class IonLocalDateSerializer extends StdScalarSerializer<LocalDate> {
      
          public IonLocalDateSerializer() {
              super(LocalDate.class);
          }
      
          @Override
          public void serialize(LocalDate date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
              Timestamp timestamp = Timestamp.forDay(date.getYear(), date.getMonthValue(), date.getDayOfMonth());
              ((IonGenerator) jsonGenerator).writeValue(timestamp);
          }
      }
      ```

1. `vehicle-registration` 테이블에 삽입한 샘플 데이터를 나타내는 다음 파일(`SampleData.java`)을 검토하세요.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial.model;
   
   import com.amazon.ion.IonString;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import java.io.IOException;
   import java.math.BigDecimal;
   import java.text.ParseException;
   import java.time.LocalDate;
   import java.time.format.DateTimeFormatter;
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.Collections;
   import java.util.List;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.ConnectToLedger;
   import software.amazon.qldb.tutorial.Constants;
   import software.amazon.qldb.tutorial.qldb.DmlResultDocument;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   
   /**
    * Sample domain objects for use throughout this tutorial.
    */
   public final class SampleData {
       public static final DateTimeFormatter DATE_TIME_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd");
   
       public static final List<VehicleRegistration> REGISTRATIONS = Collections.unmodifiableList(Arrays.asList(
               new VehicleRegistration("1N4AL11D75C109151", "LEWISR261LL", "WA", "Seattle",
                       BigDecimal.valueOf(90.25), convertToLocalDate("2017-08-21"), convertToLocalDate("2020-05-11"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("KM8SRDHF6EU074761", "CA762X", "WA", "Kent",
                       BigDecimal.valueOf(130.75), convertToLocalDate("2017-09-14"), convertToLocalDate("2020-06-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("3HGGK5G53FM761765", "CD820Z", "WA", "Everett",
                       BigDecimal.valueOf(442.30), convertToLocalDate("2011-03-17"), convertToLocalDate("2021-03-24"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1HVBBAANXWH544237", "LS477D", "WA", "Tacoma",
                       BigDecimal.valueOf(42.20), convertToLocalDate("2011-10-26"), convertToLocalDate("2023-09-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1C4RJFAG0FC625797", "TH393F", "WA", "Olympia",
                       BigDecimal.valueOf(30.45), convertToLocalDate("2013-09-02"), convertToLocalDate("2024-03-19"),
                       new Owners(new Owner(null), Collections.emptyList()))
       ));
   
       public static final List<Vehicle> VEHICLES = Collections.unmodifiableList(Arrays.asList(
               new Vehicle("1N4AL11D75C109151", "Sedan", 2011,  "Audi", "A5", "Silver"),
               new Vehicle("KM8SRDHF6EU074761", "Sedan", 2015, "Tesla", "Model S", "Blue"),
               new Vehicle("3HGGK5G53FM761765", "Motorcycle", 2011, "Ducati", "Monster 1200", "Yellow"),
               new Vehicle("1HVBBAANXWH544237", "Semi", 2009, "Ford", "F 150", "Black"),
               new Vehicle("1C4RJFAG0FC625797", "Sedan", 2019, "Mercedes", "CLK 350", "White")
       ));
   
       public static final List<Person> PEOPLE = Collections.unmodifiableList(Arrays.asList(
               new Person("Raul", "Lewis", convertToLocalDate("1963-08-19"),
                       "LEWISR261LL", "Driver License",  "1719 University Street, Seattle, WA, 98109"),
               new Person("Brent", "Logan", convertToLocalDate("1967-07-03"),
                       "LOGANB486CG", "Driver License", "43 Stockert Hollow Road, Everett, WA, 98203"),
               new Person("Alexis", "Pena", convertToLocalDate("1974-02-10"),
                       "744 849 301", "SSN", "4058 Melrose Street, Spokane Valley, WA, 99206"),
               new Person("Melvin", "Parker", convertToLocalDate("1976-05-22"),
                       "P626-168-229-765", "Passport", "4362 Ryder Avenue, Seattle, WA, 98101"),
               new Person("Salvatore", "Spencer", convertToLocalDate("1997-11-15"),
                       "S152-780-97-415-0", "Passport", "4450 Honeysuckle Lane, Seattle, WA, 98101")
       ));
   
       public static final List<DriversLicense> LICENSES = Collections.unmodifiableList(Arrays.asList(
               new DriversLicense(null, "LEWISR261LL", "Learner",
                       convertToLocalDate("2016-12-20"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "LOGANB486CG", "Probationary",
                       convertToLocalDate("2016-04-06"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "744 849 301", "Full",
                       convertToLocalDate("2017-12-06"), convertToLocalDate("2022-10-15")),
               new DriversLicense(null, "P626-168-229-765", "Learner",
                       convertToLocalDate("2017-08-16"), convertToLocalDate("2021-11-15")),
               new DriversLicense(null, "S152-780-97-415-0", "Probationary",
                       convertToLocalDate("2015-08-15"), convertToLocalDate("2021-08-21"))
       ));
   
       private SampleData() { }
   
       /**
        * Converts a date string with the format 'yyyy-MM-dd' into a {@link java.util.Date} object.
        *
        * @param date
        *              The date string to convert.
        * @return {@link java.time.LocalDate} or null if there is a {@link ParseException}
        */
       public static synchronized LocalDate convertToLocalDate(String date) {
           return LocalDate.parse(date, DATE_TIME_FORMAT);
       }
   
       /**
        * Convert the result set into a list of IonValues.
        *
        * @param result
        *              The result set to convert.
        * @return a list of IonValues.
        */
       public static List<IonValue> toIonValues(Result result) {
           final List<IonValue> valueList = new ArrayList<>();
           result.iterator().forEachRemaining(valueList::add);
           return valueList;
       }
   
       /**
        * Get the document ID of a particular document.
        *
        * @param txn
        *              A transaction executor object.
        * @param tableName
        *              Name of the table containing the document.
        * @param identifier
        *              The identifier used to narrow down the search.
        * @param value
        *              Value of the identifier.
        * @return the list of document IDs in the result set.
        */
       public static String getDocumentId(final TransactionExecutor txn, final String tableName,
                                          final String identifier, final String value) {
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(value));
               final String query = String.format("SELECT metadata.id FROM _ql_committed_%s AS p WHERE p.data.%s = ?",
                       tableName, identifier);
               Result result = txn.execute(query, parameters);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document ID using " + value);
               }
               return getStringValueOfStructField((IonStruct) result.iterator().next(), "id");
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the document by ID.
        *
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link QldbRevision} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static QldbRevision getDocumentById(String tableName, String documentId) {
           try {
               final IonValue ionValue = Constants.MAPPER.writeValueAsIonValue(documentId);
               Result result = ConnectToLedger.getDriver().execute(txn -> {
                   return txn.execute("SELECT c.* FROM _ql_committed_" + tableName + " AS c BY docId "
                                      + "WHERE docId = ?", ionValue);
               });
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document by id " + documentId + " in table " + tableName);
               }
               return Constants.MAPPER.readValue(result.iterator().next(), QldbRevision.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Return a list of modified document IDs as strings from a DML {@link Result}.
        *
        * @param result
        *              The result set from a DML operation.
        * @return the list of document IDs modified by the operation.
        */
       public static List<String> getDocumentIdsFromDmlResult(final Result result) {
           final List<String> strings = new ArrayList<>();
           result.iterator().forEachRemaining(row -> strings.add(getDocumentIdFromDmlResultDocument(row)));
           return strings;
       }
   
       /**
        * Convert the given DML result row's document ID to string.
        *
        * @param dmlResultDocument
        *              The {@link IonValue} representing the results of a DML operation.
        * @return a string of document ID.
        */
       public static String getDocumentIdFromDmlResultDocument(final IonValue dmlResultDocument) {
           try {
               DmlResultDocument result = Constants.MAPPER.readValue(dmlResultDocument, DmlResultDocument.class);
               return result.getDocumentId();
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the String value of a given {@link IonStruct} field name.
        * @param struct the {@link IonStruct} from which to get the value.
        * @param fieldName the name of the field from which to get the value.
        * @return the String value of the field within the given {@link IonStruct}.
        */
       public static String getStringValueOfStructField(final IonStruct struct, final String fieldName) {
           return ((IonString) struct.get(fieldName)).stringValue();
       }
   
       /**
        * Return a copy of the given driver's license with updated person Id.
        *
        * @param oldLicense
        *              The old driver's license to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link DriversLicense}.
        */
       public static DriversLicense updatePersonIdDriversLicense(final DriversLicense oldLicense, final String personId) {
           return new DriversLicense(personId, oldLicense.getLicenseNumber(), oldLicense.getLicenseType(),
                   oldLicense.getValidFromDate(), oldLicense.getValidToDate());
       }
   
       /**
        * Return a copy of the given vehicle registration with updated person Id.
        *
        * @param oldRegistration
        *              The old vehicle registration to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link VehicleRegistration}.
        */
       public static VehicleRegistration updateOwnerVehicleRegistration(final VehicleRegistration oldRegistration,
                                                                        final String personId) {
           return new VehicleRegistration(oldRegistration.getVin(), oldRegistration.getLicensePlateNumber(),
                   oldRegistration.getState(), oldRegistration.getCity(), oldRegistration.getPendingPenaltyTicketAmount(),
                   oldRegistration.getValidFromDate(), oldRegistration.getValidToDate(),
                   new Owners(new Owner(personId), Collections.emptyList()));
       }
   }
   ```

------
#### [ 1.x ]

**중요**  
Amazon Ion 패키지의 경우 애플리케이션에서 네임스페이스 `com.amazon.ion`을 사용해야 합니다. 는 네임스페이스 아래의 다른 Ion 패키지에 AWS SDK for Java 종속되지만 `software.amazon.ion`QLDB 드라이버와 호환되지 않는 레거시 패키지입니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial.model;
   
   import com.amazon.ion.IonString;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.Constants;
   import software.amazon.qldb.tutorial.qldb.DmlResultDocument;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   
   import java.io.IOException;
   
   import java.math.BigDecimal;
   import java.text.ParseException;
   import java.time.LocalDate;
   import java.time.format.DateTimeFormatter;
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Sample domain objects for use throughout this tutorial.
    */
   public final class SampleData {
       public static final DateTimeFormatter DATE_TIME_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd");
   
       public static final List<VehicleRegistration> REGISTRATIONS = Collections.unmodifiableList(Arrays.asList(
               new VehicleRegistration("1N4AL11D75C109151", "LEWISR261LL", "WA", "Seattle",
                       BigDecimal.valueOf(90.25), convertToLocalDate("2017-08-21"), convertToLocalDate("2020-05-11"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("KM8SRDHF6EU074761", "CA762X", "WA", "Kent",
                       BigDecimal.valueOf(130.75), convertToLocalDate("2017-09-14"), convertToLocalDate("2020-06-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("3HGGK5G53FM761765", "CD820Z", "WA", "Everett",
                       BigDecimal.valueOf(442.30), convertToLocalDate("2011-03-17"), convertToLocalDate("2021-03-24"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1HVBBAANXWH544237", "LS477D", "WA", "Tacoma",
                       BigDecimal.valueOf(42.20), convertToLocalDate("2011-10-26"), convertToLocalDate("2023-09-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1C4RJFAG0FC625797", "TH393F", "WA", "Olympia",
                       BigDecimal.valueOf(30.45), convertToLocalDate("2013-09-02"), convertToLocalDate("2024-03-19"),
                       new Owners(new Owner(null), Collections.emptyList()))
       ));
   
       public static final List<Vehicle> VEHICLES = Collections.unmodifiableList(Arrays.asList(
               new Vehicle("1N4AL11D75C109151", "Sedan", 2011,  "Audi", "A5", "Silver"),
               new Vehicle("KM8SRDHF6EU074761", "Sedan", 2015, "Tesla", "Model S", "Blue"),
               new Vehicle("3HGGK5G53FM761765", "Motorcycle", 2011, "Ducati", "Monster 1200", "Yellow"),
               new Vehicle("1HVBBAANXWH544237", "Semi", 2009, "Ford", "F 150", "Black"),
               new Vehicle("1C4RJFAG0FC625797", "Sedan", 2019, "Mercedes", "CLK 350", "White")
       ));
   
       public static final List<Person> PEOPLE = Collections.unmodifiableList(Arrays.asList(
               new Person("Raul", "Lewis", convertToLocalDate("1963-08-19"),
                       "LEWISR261LL", "Driver License",  "1719 University Street, Seattle, WA, 98109"),
               new Person("Brent", "Logan", convertToLocalDate("1967-07-03"),
                       "LOGANB486CG", "Driver License", "43 Stockert Hollow Road, Everett, WA, 98203"),
               new Person("Alexis", "Pena", convertToLocalDate("1974-02-10"),
                       "744 849 301", "SSN", "4058 Melrose Street, Spokane Valley, WA, 99206"),
               new Person("Melvin", "Parker", convertToLocalDate("1976-05-22"),
                       "P626-168-229-765", "Passport", "4362 Ryder Avenue, Seattle, WA, 98101"),
               new Person("Salvatore", "Spencer", convertToLocalDate("1997-11-15"),
                       "S152-780-97-415-0", "Passport", "4450 Honeysuckle Lane, Seattle, WA, 98101")
       ));
   
       public static final List<DriversLicense> LICENSES = Collections.unmodifiableList(Arrays.asList(
               new DriversLicense(null, "LEWISR261LL", "Learner",
                       convertToLocalDate("2016-12-20"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "LOGANB486CG", "Probationary",
                       convertToLocalDate("2016-04-06"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "744 849 301", "Full",
                       convertToLocalDate("2017-12-06"), convertToLocalDate("2022-10-15")),
               new DriversLicense(null, "P626-168-229-765", "Learner",
                       convertToLocalDate("2017-08-16"), convertToLocalDate("2021-11-15")),
               new DriversLicense(null, "S152-780-97-415-0", "Probationary",
                       convertToLocalDate("2015-08-15"), convertToLocalDate("2021-08-21"))
       ));
   
       private SampleData() { }
   
       /**
        * Converts a date string with the format 'yyyy-MM-dd' into a {@link java.util.Date} object.
        *
        * @param date
        *              The date string to convert.
        * @return {@link LocalDate} or null if there is a {@link ParseException}
        */
       public static synchronized LocalDate convertToLocalDate(String date) {
           return LocalDate.parse(date, DATE_TIME_FORMAT);
       }
   
       /**
        * Convert the result set into a list of IonValues.
        *
        * @param result
        *              The result set to convert.
        * @return a list of IonValues.
        */
       public static List<IonValue> toIonValues(Result result) {
           final List<IonValue> valueList = new ArrayList<>();
           result.iterator().forEachRemaining(valueList::add);
           return valueList;
       }
   
       /**
        * Get the document ID of a particular document.
        *
        * @param txn
        *              A transaction executor object.
        * @param tableName
        *              Name of the table containing the document.
        * @param identifier
        *              The identifier used to narrow down the search.
        * @param value
        *              Value of the identifier.
        * @return the list of document IDs in the result set.
        */
       public static String getDocumentId(final TransactionExecutor txn, final String tableName,
                                          final String identifier, final String value) {
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(value));
               final String query = String.format("SELECT metadata.id FROM _ql_committed_%s AS p WHERE p.data.%s = ?",
                       tableName, identifier);
               Result result = txn.execute(query, parameters);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document ID using " + value);
               }
               return getStringValueOfStructField((IonStruct) result.iterator().next(), "id");
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the document by ID.
        *
        * @param qldbSession
        *              A QLDB session.
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link QldbRevision} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static QldbRevision getDocumentById(QldbSession qldbSession, String tableName, String documentId) {
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(documentId));
               final String query = String.format("SELECT c.* FROM _ql_committed_%s AS c BY docId WHERE docId = ?", tableName);
               Result result = qldbSession.execute(query, parameters);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document by id " + documentId + " in table " + tableName);
               }
               return Constants.MAPPER.readValue(result.iterator().next(), QldbRevision.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Return a list of modified document IDs as strings from a DML {@link Result}.
        *
        * @param result
        *              The result set from a DML operation.
        * @return the list of document IDs modified by the operation.
        */
       public static List<String> getDocumentIdsFromDmlResult(final Result result) {
           final List<String> strings = new ArrayList<>();
           result.iterator().forEachRemaining(row -> strings.add(getDocumentIdFromDmlResultDocument(row)));
           return strings;
       }
   
       /**
        * Convert the given DML result row's document ID to string.
        *
        * @param dmlResultDocument
        *              The {@link IonValue} representing the results of a DML operation.
        * @return a string of document ID.
        */
       public static String getDocumentIdFromDmlResultDocument(final IonValue dmlResultDocument) {
           try {
               DmlResultDocument result = Constants.MAPPER.readValue(dmlResultDocument, DmlResultDocument.class);
               return result.getDocumentId();
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the String value of a given {@link IonStruct} field name.
        * @param struct the {@link IonStruct} from which to get the value.
        * @param fieldName the name of the field from which to get the value.
        * @return the String value of the field within the given {@link IonStruct}.
        */
       public static String getStringValueOfStructField(final IonStruct struct, final String fieldName) {
           return ((IonString) struct.get(fieldName)).stringValue();
       }
   
       /**
        * Return a copy of the given driver's license with updated person Id.
        *
        * @param oldLicense
        *              The old driver's license to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link DriversLicense}.
        */
       public static DriversLicense updatePersonIdDriversLicense(final DriversLicense oldLicense, final String personId) {
           return new DriversLicense(personId, oldLicense.getLicenseNumber(), oldLicense.getLicenseType(),
                   oldLicense.getValidFromDate(), oldLicense.getValidToDate());
       }
   
       /**
        * Return a copy of the given vehicle registration with updated person Id.
        *
        * @param oldRegistration
        *              The old vehicle registration to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link VehicleRegistration}.
        */
       public static VehicleRegistration updateOwnerVehicleRegistration(final VehicleRegistration oldRegistration,
                                                                        final String personId) {
           return new VehicleRegistration(oldRegistration.getVin(), oldRegistration.getLicensePlateNumber(),
                   oldRegistration.getState(), oldRegistration.getCity(), oldRegistration.getPendingPenaltyTicketAmount(),
                   oldRegistration.getValidFromDate(), oldRegistration.getValidToDate(),
                   new Owners(new Owner(personId), Collections.emptyList()));
       }
   }
   ```

------
**참고**  
이 클래스는 Ion 라이브러리를 사용하여 데이터를 Ion 형식으로 또는 Ion 형식에서 변환하는 도우미 메서드를 제공합니다.
이 `getDocumentId` 메서드는 접두사 `_ql_committed_`가 있는 테이블에 대한 쿼리를 실행합니다. 이는 테이블의 *커밋된 보기*를 쿼리하려는 것을 나타내는 예약된 접두사입니다. 이 뷰에서는 데이터가 `data` 필드에 중첩되고 메타데이터는 `metadata` 필드에 중첩됩니다.

1. 다음 프로그램(`CreateTable.java`)을 컴파일하고 실행하여 앞서 언급한 테이블을 생성합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create tables in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateTable {
       public static final Logger log = LoggerFactory.getLogger(CreateTable.class);
   
       private CreateTable() { }
   
       /**
        * Registrations, vehicles, owners, and licenses tables being created in a single transaction.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @return the number of tables created.
        */
       public static int createTable(final TransactionExecutor txn, final String tableName) {
           log.info("Creating the '{}' table...", tableName);
           final String createTable = String.format("CREATE TABLE %s", tableName);
           final Result result = txn.execute(createTable);
           log.info("{} table created successfully.", tableName);
           return SampleData.toIonValues(result).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createTable(txn, Constants.DRIVERS_LICENSE_TABLE_NAME);
               createTable(txn, Constants.PERSON_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           });
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create tables in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateTable {
       public static final Logger log = LoggerFactory.getLogger(CreateTable.class);
   
       private CreateTable() { }
   
       /**
        * Registrations, vehicles, owners, and licenses tables being created in a single transaction.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @return the number of tables created.
        */
       public static int createTable(final TransactionExecutor txn, final String tableName) {
           log.info("Creating the '{}' table...", tableName);
           final String createTable = String.format("CREATE TABLE %s", tableName);
           final Result result = txn.execute(createTable);
           log.info("{} table created successfully.", tableName);
           return SampleData.toIonValues(result).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createTable(txn, Constants.DRIVERS_LICENSE_TABLE_NAME);
               createTable(txn, Constants.PERSON_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
       }
   }
   ```

------
**참고**  
이 프로그램은 `TransactionExecutor` Lambda를 `execute` 메서드에 전달하는 방법을 보여줍니다. 이 예제에서는 Lambda 표현식을 사용하여 단일 트랜잭션에서 여러 `CREATE TABLE` PartiQL 명령문을 실행합니다.  
`execute` 메서드는 암시적으로 트랜잭션을 시작하고 Lambda에서 모든 문을 실행한 다음 트랜잭션을 자동 커밋합니다.

1. 앞에서 설명한 대로 다음 프로그램(`CreateIndex.java`)을 컴파일하고 실행하여 테이블에 인덱스를 생성합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create indexes on tables in a particular ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateIndex {
       public static final Logger log = LoggerFactory.getLogger(CreateIndex.class);
   
       private CreateIndex() { }
   
       /**
        * In this example, create indexes for registrations and vehicles tables.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @param indexAttribute
        *              The index attribute to use.
        * @return the number of tables created.
        */
       public static int createIndex(final TransactionExecutor txn, final String tableName, final String indexAttribute) {
           log.info("Creating an index on {}...", indexAttribute);
           final String createIndex = String.format("CREATE INDEX ON %s (%s)", tableName, indexAttribute);
           final Result r = txn.execute(createIndex);
           return SampleData.toIonValues(r).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createIndex(txn, Constants.PERSON_TABLE_NAME, Constants.PERSON_GOV_ID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_NUMBER_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_PERSONID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Constants.VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME);
           });
           log.info("Indexes created successfully!");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create indexes on tables in a particular ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateIndex {
       public static final Logger log = LoggerFactory.getLogger(CreateIndex.class);
   
       private CreateIndex() { }
   
       /**
        * In this example, create indexes for registrations and vehicles tables.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @param indexAttribute
        *              The index attribute to use.
        * @return the number of tables created.
        */
       public static int createIndex(final TransactionExecutor txn, final String tableName, final String indexAttribute) {
           log.info("Creating an index on {}...", indexAttribute);
           final String createIndex = String.format("CREATE INDEX ON %s (%s)", tableName, indexAttribute);
           final Result r = txn.execute(createIndex);
           return SampleData.toIonValues(r).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createIndex(txn, Constants.PERSON_TABLE_NAME, Constants.PERSON_GOV_ID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_NUMBER_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_PERSONID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Constants.VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Indexes created successfully!");
       }
   }
   ```

------

1. 다음 프로그램(`InsertDocument.java`)을 컴파일하고 실행하여 샘플 데이터를 테이블에 삽입합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.DriversLicense;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   /**
    * Insert documents into a table in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class InsertDocument {
       public static final Logger log = LoggerFactory.getLogger(InsertDocument.class);
   
       private InsertDocument() { }
   
       /**
        * Insert the given list of documents into the specified table and return the document IDs of the inserted documents.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documents
        *              List of documents to insert into the specified table.
        * @return a list of document IDs.
        * @throws IllegalStateException if failed to convert documents into an {@link IonValue}.
        */
       public static List<String> insertDocuments(final TransactionExecutor txn, final String tableName,
                                                  final List documents) {
           log.info("Inserting some documents in the {} table...", tableName);
           try {
               final String query = String.format("INSERT INTO %s ?", tableName);
               final IonValue ionDocuments = Constants.MAPPER.writeValueAsIonValue(documents);
   
               return SampleData.getDocumentIdsFromDmlResult(txn.execute(query, ionDocuments));
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update PersonIds in driver's licenses and in vehicle registrations using document IDs.
        *
        * @param documentIds
        *              List of document IDs representing the PersonIds in DriversLicense and PrimaryOwners in VehicleRegistration.
        * @param licenses
        *              List of driver's licenses to update.
        * @param registrations
        *              List of registrations to update.
        */
       public static void updatePersonId(final List<String> documentIds, final List<DriversLicense> licenses,
                                         final List<VehicleRegistration> registrations) {
           for (int i = 0; i < documentIds.size(); ++i) {
               DriversLicense license = SampleData.LICENSES.get(i);
               VehicleRegistration registration = SampleData.REGISTRATIONS.get(i);
               licenses.add(SampleData.updatePersonIdDriversLicense(license, documentIds.get(i)));
               registrations.add(SampleData.updateOwnerVehicleRegistration(registration, documentIds.get(i)));
           }
       }
   
       public static void main(final String... args) {
           final List<DriversLicense> newDriversLicenses = new ArrayList<>();
           final List<VehicleRegistration> newVehicleRegistrations = new ArrayList<>();
           ConnectToLedger.getDriver().execute(txn -> {
               List<String> documentIds = insertDocuments(txn, Constants.PERSON_TABLE_NAME, SampleData.PEOPLE);
               updatePersonId(documentIds, newDriversLicenses, newVehicleRegistrations);
               insertDocuments(txn, Constants.VEHICLE_TABLE_NAME, SampleData.VEHICLES);
               insertDocuments(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Collections.unmodifiableList(newVehicleRegistrations));
               insertDocuments(txn, Constants.DRIVERS_LICENSE_TABLE_NAME,
                       Collections.unmodifiableList(newDriversLicenses));
           });
           log.info("Documents inserted successfully!");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonValue;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.DriversLicense;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Insert documents into a table in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class InsertDocument {
       public static final Logger log = LoggerFactory.getLogger(InsertDocument.class);
   
       private InsertDocument() { }
   
       /**
        * Insert the given list of documents into the specified table and return the document IDs of the inserted documents.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documents
        *              List of documents to insert into the specified table.
        * @return a list of document IDs.
        * @throws IllegalStateException if failed to convert documents into an {@link IonValue}.
        */
       public static List<String> insertDocuments(final TransactionExecutor txn, final String tableName,
                                                  final List documents) {
           log.info("Inserting some documents in the {} table...", tableName);
           try {
               final String statement = String.format("INSERT INTO %s ?", tableName);
               final IonValue ionDocuments = Constants.MAPPER.writeValueAsIonValue(documents);
               final List<IonValue> parameters = Collections.singletonList(ionDocuments);
               return SampleData.getDocumentIdsFromDmlResult(txn.execute(statement, parameters));
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update PersonIds in driver's licenses and in vehicle registrations using document IDs.
        *
        * @param documentIds
        *              List of document IDs representing the PersonIds in DriversLicense and PrimaryOwners in VehicleRegistration.
        * @param licenses
        *              List of driver's licenses to update.
        * @param registrations
        *              List of registrations to update.
        */
       public static void updatePersonId(final List<String> documentIds, final List<DriversLicense> licenses,
                                         final List<VehicleRegistration> registrations) {
           for (int i = 0; i < documentIds.size(); ++i) {
               DriversLicense license = SampleData.LICENSES.get(i);
               VehicleRegistration registration = SampleData.REGISTRATIONS.get(i);
               licenses.add(SampleData.updatePersonIdDriversLicense(license, documentIds.get(i)));
               registrations.add(SampleData.updateOwnerVehicleRegistration(registration, documentIds.get(i)));
           }
       }
   
       public static void main(final String... args) {
           final List<DriversLicense> newDriversLicenses = new ArrayList<>();
           final List<VehicleRegistration> newVehicleRegistrations = new ArrayList<>();
           ConnectToLedger.getDriver().execute(txn -> {
               List<String> documentIds = insertDocuments(txn, Constants.PERSON_TABLE_NAME, SampleData.PEOPLE);
               updatePersonId(documentIds, newDriversLicenses, newVehicleRegistrations);
               insertDocuments(txn, Constants.VEHICLE_TABLE_NAME, SampleData.VEHICLES);
               insertDocuments(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Collections.unmodifiableList(newVehicleRegistrations));
               insertDocuments(txn, Constants.DRIVERS_LICENSE_TABLE_NAME,
                       Collections.unmodifiableList(newDriversLicenses));
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Documents inserted successfully!");
       }
   }
   ```

------
**참고**  
이 프로그램은 파라미터화된 값을 사용하여 `execute` 메서드를 호출하는 방법을 보여줍니다. 실행하려는 PartiQL 문 외에도 `IonValue` 유형의 데이터 파라미터를 전달할 수 있습니다. 명령문 문자열에서 물음표(`?`)를 변수 자리 표시자로 사용하세요.
`INSERT` 문이 성공하면 삽입된 각 문서의 `id`이 반환됩니다.

다음으로, `SELECT` 문을 사용하여 `vehicle-registration` 원장의 테이블에서 데이터를 읽을 수 있습니다. [4단계: 원장에서 테이블 쿼리](getting-started.java.step-4.md)로 이동합니다.

# 4단계: 원장에서 테이블 쿼리
<a name="getting-started.java.step-4"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB 원장에 테이블을 생성하고 데이터를 로드한 후 쿼리를 실행하여 방금 삽입한 차량 등록 데이터를 검토할 수 있습니다. QLDB는 [PartiQL](ql-reference.md)을 쿼리 언어로 사용하고 [Amazon Ion](ion.md)을 문서 지향 데이터 모델로 사용합니다.

PartiQL은 Ion과 함께 작동하도록 확장된 오픈 소스 SQL 호환 쿼리 언어입니다. PartiQL을 사용하면 익숙한 SQL 연산자를 사용하여 데이터를 삽입, 쿼리 및 관리할 수 있습니다. Amazon Ion은 JSON의 상위 집합입니다. Ion은 정형, 반정형 및 중첩 데이터를 저장하고 처리할 수 있는 유연성을 제공하는 오픈 소스 문서 기반 데이터 형식입니다.

이 단계에서는 `SELECT` 명령문을 사용하여 `vehicle-registration` 원장의 테이블에서 데이터를 읽습니다.

**주의**  
인덱싱된 조회 없이 QLDB에서 쿼리를 실행하면 전체 테이블 스캔이 호출됩니다. PartiQL은 SQL과 호환되므로 이러한 쿼리를 지원합니다. 하지만 QLDB의 프로덕션 사용 사례에 대해서는 테이블 스캔을 실행하지 *마세요.*. 테이블 스캔은 동시성 충돌 및 트랜잭션 시간 초과를 포함하여 대규모 테이블에서 성능 문제를 일으킬 수 있습니다.  
인덱싱된 필드 또는 문서 ID(예: `WHERE indexedField = 123` 또는 `WHERE indexedField IN (456, 789)`)에서 동등 *연산자*를 사용하여 `WHERE` 조건자 절이 포함된 문을 실행하는 것이 좋습니다. 자세한 내용은 [쿼리 성능 최적화](working.optimize.md)을 참조하세요.

**테이블을 쿼리하려면**
+ 다음 프로그램(`FindVehicles.java`)을 컴파일하고 실행하여 원장에 있는 사람의 이름으로 등록된 모든 차량을 쿼리하세요.

------
#### [ 2.x ]

  ```
  /*
   * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   * SPDX-License-Identifier: MIT-0
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of this
   * software and associated documentation files (the "Software"), to deal in the Software
   * without restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  package software.amazon.qldb.tutorial;
  
  import java.io.IOException;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.amazon.ion.IonValue;
  
  import software.amazon.qldb.Result;
  import software.amazon.qldb.TransactionExecutor;
  import software.amazon.qldb.tutorial.model.Person;
  import software.amazon.qldb.tutorial.model.SampleData;
  
  /**
   * Find all vehicles registered under a person.
   *
   * This code expects that you have AWS credentials setup per:
   * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
   */
  public final class FindVehicles {
      public static final Logger log = LoggerFactory.getLogger(FindVehicles.class);
  
      private FindVehicles() { }
  
      /**
       * Find vehicles registered under a driver using their government ID.
       *
       * @param txn
       *              The {@link TransactionExecutor} for lambda execute.
       * @param govId
       *              The government ID of the owner.
       * @throws IllegalStateException if failed to convert parameters into {@link IonValue}.
       */
      public static void findVehiclesForOwner(final TransactionExecutor txn, final String govId) {
          try {
              final String documentId = Person.getDocumentIdByGovId(txn, govId);
              final String query = "SELECT v FROM Vehicle AS v INNER JOIN VehicleRegistration AS r "
                      + "ON v.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?";
  
              final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
              log.info("List of Vehicles for owner with GovId: {}...", govId);
              ScanTable.printDocuments(result);
          } catch (IOException ioe) {
              throw new IllegalStateException(ioe);
          }
      }
  
      public static void main(final String... args) {
          final Person person = SampleData.PEOPLE.get(0);
          ConnectToLedger.getDriver().execute(txn -> {
              findVehiclesForOwner(txn, person.getGovId());
          });
      }
  }
  ```

------
#### [ 1.x ]

  ```
  /*
   * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
   * SPDX-License-Identifier: MIT-0
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of this
   * software and associated documentation files (the "Software"), to deal in the Software
   * without restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  package software.amazon.qldb.tutorial;
  
  import java.io.IOException;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.amazon.ion.IonValue;
  
  import software.amazon.qldb.Result;
  import software.amazon.qldb.TransactionExecutor;
  import software.amazon.qldb.tutorial.model.Person;
  import software.amazon.qldb.tutorial.model.SampleData;
  
  /**
   * Find all vehicles registered under a person.
   *
   * This code expects that you have AWS credentials setup per:
   * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
   */
  public final class FindVehicles {
      public static final Logger log = LoggerFactory.getLogger(FindVehicles.class);
  
      private FindVehicles() { }
  
      /**
       * Find vehicles registered under a driver using their government ID.
       *
       * @param txn
       *              The {@link TransactionExecutor} for lambda execute.
       * @param govId
       *              The government ID of the owner.
       * @throws IllegalStateException if failed to convert parameters into {@link IonValue}.
       */
      public static void findVehiclesForOwner(final TransactionExecutor txn, final String govId) {
          try {
              final String documentId = Person.getDocumentIdByGovId(txn, govId);
              final String query = "SELECT v FROM Vehicle AS v INNER JOIN VehicleRegistration AS r "
                      + "ON v.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?";
  
              final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
              log.info("List of Vehicles for owner with GovId: {}...", govId);
              ScanTable.printDocuments(result);
          } catch (IOException ioe) {
              throw new IllegalStateException(ioe);
          }
      }
  
      public static void main(final String... args) {
          final Person person = SampleData.PEOPLE.get(0);
          ConnectToLedger.getDriver().execute(txn -> {
              findVehiclesForOwner(txn, person.getGovId());
          }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
      }
  }
  ```

------
**참고**  
먼저 이 프로그램은 이 문서에 대한 `Person` 테이블을 `GovId LEWISR261LL`로 쿼리하여 `id` 메타데이터 필드를 가져옵니다.  
그런 다음 이 문서 `id`를 외래 키로 사용하여 `VehicleRegistration` 테이블을 `PrimaryOwner.PersonId`로 쿼리합니다. 또한 `VIN` 필드의 `Vehicle` 테이블과 `VehicleRegistration`를 조인합니다.

`vehicle-registration` 원장의 테이블에 있는 문서를 수정하는 방법에 대한 자세한 내용은 [5단계: 원장의 문서 수정](getting-started.java.step-5.md)을 참조하세요.

# 5단계: 원장의 문서 수정
<a name="getting-started.java.step-5"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이제 작업할 데이터가 있으므로 Amazon QLDB에서 `vehicle-registration` 원장에 있는 문서를 변경할 수 있습니다. 이 단계에서 다음 코드 예제는 DML(데이터 조작 언어) 문을 실행하는 방법을 보여줍니다. 이러한 명령문은 한 차량의 주 소유자를 업데이트하고 다른 차량에 보조 소유자를 추가합니다.

**문서를 수정하려면**

1. 다음 프로그램(`TransferVehicleOwnership.java`)을 컴파일하고 실행하여 차량의 기본 소유주를 원장의 VIN `1N4AL11D75C109151`으로 업데이트합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.system.IonReaderBuilder;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.LinkedHashMap;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Find primary owner for a particular vehicle's VIN.
    * Transfer to another primary owner for a particular vehicle's VIN.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class TransferVehicleOwnership {
       public static final Logger log = LoggerFactory.getLogger(TransferVehicleOwnership.class);
   
       private TransferVehicleOwnership() { }
   
       /**
        * Query a driver's information using the given ID.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPersonFromDocumentId(final TransactionExecutor txn, final String documentId) {
           try {
               log.info("Finding person for documentId: {}...", documentId);
               final String query = "SELECT p.* FROM Person AS p BY pid WHERE pid = ?";
   
               Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to find person with ID: " + documentId);
               }
   
               return Constants.MAPPER.readValue(result.iterator().next(), Person.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Find the primary owner for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPrimaryOwnerForVehicle(final TransactionExecutor txn, final String vin) {
           try {
               log.info("Finding primary owner for vehicle with Vin: {}...", vin);
               final String query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               Result result = txn.execute(query, parameters);
               final List<IonStruct> documents = ScanTable.toIonStructs(result);
               ScanTable.printDocuments(documents);
               if (documents.isEmpty()) {
                   throw new IllegalStateException("Unable to find registrations with VIN: " + vin);
               }
   
               final IonReader reader = IonReaderBuilder.standard().build(documents.get(0));
               final String personId = Constants.MAPPER.readValue(reader, LinkedHashMap.class).get("PersonId").toString();
               return findPersonFromDocumentId(txn, personId);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update the primary owner for a vehicle registration with the given documentId.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param documentId
        *              New PersonId for the primary owner.
        * @throws IllegalStateException if no vehicle registration was found using the given document ID and VIN, or if failed
        * to convert parameters into {@link IonValue}.
        */
       public static void updateVehicleRegistration(final TransactionExecutor txn, final String vin, final String documentId) {
           try {
               log.info("Updating primary owner for vehicle with Vin: {}...", vin);
               final String query = "UPDATE VehicleRegistration AS v SET v.Owners.PrimaryOwner = ? WHERE v.VIN = ?";
   
               final List<IonValue> parameters = new ArrayList<>();
               parameters.add(Constants.MAPPER.writeValueAsIonValue(new Owner(documentId)));
               parameters.add(Constants.MAPPER.writeValueAsIonValue(vin));
   
               Result result = txn.execute(query, parameters);
               ScanTable.printDocuments(result);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to transfer vehicle, could not find registration.");
               } else {
                   log.info("Successfully transferred vehicle with VIN '{}' to new owner.", vin);
               }
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(0).getVin();
           final String primaryOwnerGovId = SampleData.PEOPLE.get(0).getGovId();
           final String newPrimaryOwnerGovId = SampleData.PEOPLE.get(1).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final Person primaryOwner = findPrimaryOwnerForVehicle(txn, vin);
               if (!primaryOwner.getGovId().equals(primaryOwnerGovId)) {
                   // Verify the primary owner.
                   throw new IllegalStateException("Incorrect primary owner identified for vehicle, unable to transfer.");
               }
   
               final String newOwner = Person.getDocumentIdByGovId(txn, newPrimaryOwnerGovId);
               updateVehicleRegistration(txn, vin, newOwner);
           });
           log.info("Successfully transferred vehicle ownership!");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.system.IonReaderBuilder;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.LinkedHashMap;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Find primary owner for a particular vehicle's VIN.
    * Transfer to another primary owner for a particular vehicle's VIN.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class TransferVehicleOwnership {
       public static final Logger log = LoggerFactory.getLogger(TransferVehicleOwnership.class);
   
       private TransferVehicleOwnership() { }
   
       /**
        * Query a driver's information using the given ID.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPersonFromDocumentId(final TransactionExecutor txn, final String documentId) {
           try {
               log.info("Finding person for documentId: {}...", documentId);
               final String query = "SELECT p.* FROM Person AS p BY pid WHERE pid = ?";
   
               Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to find person with ID: " + documentId);
               }
   
               return Constants.MAPPER.readValue(result.iterator().next(), Person.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Find the primary owner for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPrimaryOwnerForVehicle(final TransactionExecutor txn, final String vin) {
           try {
               log.info("Finding primary owner for vehicle with Vin: {}...", vin);
               final String query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               Result result = txn.execute(query, parameters);
               final List<IonStruct> documents = ScanTable.toIonStructs(result);
               ScanTable.printDocuments(documents);
               if (documents.isEmpty()) {
                   throw new IllegalStateException("Unable to find registrations with VIN: " + vin);
               }
   
               final IonReader reader = IonReaderBuilder.standard().build(documents.get(0));
               final String personId = Constants.MAPPER.readValue(reader, LinkedHashMap.class).get("PersonId").toString();
               return findPersonFromDocumentId(txn, personId);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update the primary owner for a vehicle registration with the given documentId.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param documentId
        *              New PersonId for the primary owner.
        * @throws IllegalStateException if no vehicle registration was found using the given document ID and VIN, or if failed
        * to convert parameters into {@link IonValue}.
        */
       public static void updateVehicleRegistration(final TransactionExecutor txn, final String vin, final String documentId) {
           try {
               log.info("Updating primary owner for vehicle with Vin: {}...", vin);
               final String query = "UPDATE VehicleRegistration AS v SET v.Owners.PrimaryOwner = ? WHERE v.VIN = ?";
   
               final List<IonValue> parameters = new ArrayList<>();
               parameters.add(Constants.MAPPER.writeValueAsIonValue(new Owner(documentId)));
               parameters.add(Constants.MAPPER.writeValueAsIonValue(vin));
   
               Result result = txn.execute(query, parameters);
               ScanTable.printDocuments(result);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to transfer vehicle, could not find registration.");
               } else {
                   log.info("Successfully transferred vehicle with VIN '{}' to new owner.", vin);
               }
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(0).getVin();
           final String primaryOwnerGovId = SampleData.PEOPLE.get(0).getGovId();
           final String newPrimaryOwnerGovId = SampleData.PEOPLE.get(1).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final Person primaryOwner = findPrimaryOwnerForVehicle(txn, vin);
               if (!primaryOwner.getGovId().equals(primaryOwnerGovId)) {
                   // Verify the primary owner.
                   throw new IllegalStateException("Incorrect primary owner identified for vehicle, unable to transfer.");
               }
   
               final String newOwner = Person.getDocumentIdByGovId(txn, newPrimaryOwnerGovId);
               updateVehicleRegistration(txn, vin, newOwner);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Successfully transferred vehicle ownership!");
       }
   }
   ```

------

1. 다음 프로그램(`AddSecondaryOwner.java`)을 컴파일하고 실행하여 보조 소유자를 원장의 VIN `KM8SRDHF6EU074761`로 차량에 추가합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.util.Collections;
   import java.util.Iterator;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Owners;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Finds and adds secondary owners for a vehicle.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class AddSecondaryOwner {
       public static final Logger log = LoggerFactory.getLogger(AddSecondaryOwner.class);
   
       private AddSecondaryOwner() { }
   
       /**
        * Check whether a secondary owner has already been registered for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwnerId
        *              The secondary owner to add.
        * @return {@code true} if the given secondary owner has already been registered, {@code false} otherwise.
        * @throws IllegalStateException if failed to convert VIN to an {@link IonValue}.
        */
       public static boolean isSecondaryOwnerForVehicle(final TransactionExecutor txn, final String vin,
                                                        final String secondaryOwnerId) {
           try {
               log.info("Finding secondary owners for vehicle with VIN: {}...", vin);
               final String query = "SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               final Iterator<IonValue> itr = result.iterator();
               if (!itr.hasNext()) {
                   return false;
               }
   
               final Owners owners = Constants.MAPPER.readValue(itr.next(), Owners.class);
               if (null != owners.getSecondaryOwners()) {
                   for (Owner owner : owners.getSecondaryOwners()) {
                       if (secondaryOwnerId.equalsIgnoreCase(owner.getPersonId())) {
                           return true;
                       }
                   }
               }
   
               return false;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Adds a secondary owner for the specified VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwner
        *              The secondary owner to add.
        * @throws IllegalStateException if failed to convert parameter into an {@link IonValue}.
        */
       public static void addSecondaryOwnerForVin(final TransactionExecutor txn, final String vin,
                                                  final String secondaryOwner) {
           try {
               log.info("Inserting secondary owner for vehicle with VIN: {}...", vin);
               final String query = String.format("FROM VehicleRegistration AS v WHERE v.VIN = ?" +
                       "INSERT INTO v.Owners.SecondaryOwners VALUE ?");
               final IonValue newOwner = Constants.MAPPER.writeValueAsIonValue(new Owner(secondaryOwner));
               final IonValue vinAsIonValue = Constants.MAPPER.writeValueAsIonValue(vin);
               Result result = txn.execute(query, vinAsIonValue, newOwner);
               log.info("VehicleRegistration Document IDs which had secondary owners added: ");
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(1).getVin();
           final String govId = SampleData.PEOPLE.get(0).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final String documentId = Person.getDocumentIdByGovId(txn, govId);
               if (isSecondaryOwnerForVehicle(txn, vin, documentId)) {
                   log.info("Person with ID {} has already been added as a secondary owner of this vehicle.", govId);
               } else {
                   addSecondaryOwnerForVin(txn, vin, documentId);
               }
           });
           log.info("Secondary owners successfully updated.");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.util.Collections;
   import java.util.Iterator;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Owners;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Finds and adds secondary owners for a vehicle.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class AddSecondaryOwner {
       public static final Logger log = LoggerFactory.getLogger(AddSecondaryOwner.class);
   
       private AddSecondaryOwner() { }
   
       /**
        * Check whether a secondary owner has already been registered for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwnerId
        *              The secondary owner to add.
        * @return {@code true} if the given secondary owner has already been registered, {@code false} otherwise.
        * @throws IllegalStateException if failed to convert VIN to an {@link IonValue}.
        */
       public static boolean isSecondaryOwnerForVehicle(final TransactionExecutor txn, final String vin,
                                                        final String secondaryOwnerId) {
           try {
               log.info("Finding secondary owners for vehicle with VIN: {}...", vin);
               final String query = "SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               final Iterator<IonValue> itr = result.iterator();
               if (!itr.hasNext()) {
                   return false;
               }
   
               final Owners owners = Constants.MAPPER.readValue(itr.next(), Owners.class);
               if (null != owners.getSecondaryOwners()) {
                   for (Owner owner : owners.getSecondaryOwners()) {
                       if (secondaryOwnerId.equalsIgnoreCase(owner.getPersonId())) {
                           return true;
                       }
                   }
               }
   
               return false;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Adds a secondary owner for the specified VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwner
        *              The secondary owner to add.
        * @throws IllegalStateException if failed to convert parameter into an {@link IonValue}.
        */
       public static void addSecondaryOwnerForVin(final TransactionExecutor txn, final String vin,
                                                  final String secondaryOwner) {
           try {
               log.info("Inserting secondary owner for vehicle with VIN: {}...", vin);
               final String query = String.format("FROM VehicleRegistration AS v WHERE v.VIN = '%s' " +
                       "INSERT INTO v.Owners.SecondaryOwners VALUE ?", vin);
               final IonValue newOwner = Constants.MAPPER.writeValueAsIonValue(new Owner(secondaryOwner));
               Result result = txn.execute(query, newOwner);
               log.info("VehicleRegistration Document IDs which had secondary owners added: ");
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(1).getVin();
           final String govId = SampleData.PEOPLE.get(0).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final String documentId = Person.getDocumentIdByGovId(txn, govId);
               if (isSecondaryOwnerForVehicle(txn, vin, documentId)) {
                   log.info("Person with ID {} has already been added as a secondary owner of this vehicle.", govId);
               } else {
                   addSecondaryOwnerForVin(txn, vin, documentId);
               }
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Secondary owners successfully updated.");
       }
   }
   ```

------

`vehicle-registration` 원장의 이러한 변경 사항을 검토하려면 [6단계: 문서의 개정 기록 보기](getting-started.java.step-6.md)을 참조하세요.

# 6단계: 문서의 개정 기록 보기
<a name="getting-started.java.step-6"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이전 단계에서 차량의 등록 데이터를 수정한 후 등록된 모든 소유자의 기록과 기타 업데이트된 필드를 쿼리할 수 있습니다. 이 단계에서는 `vehicle-registration` 원장의 `VehicleRegistration` 테이블에 있는 문서의 개정 기록을 쿼리합니다.

**개정 기록을 보려면**

1. 다음 프로그램(`QueryHistory.java`)을 검토합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.time.Instant;
   import java.time.temporal.ChronoUnit;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   /**
    * Query a table's history for a particular set of documents.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class QueryHistory {
       public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
       private static final int THREE_MONTHS = 90;
   
       private QueryHistory() { }
   
       /**
        * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              VIN to find previous primary owners for.
        * @param query
        *              The query to find previous primary owners.
        * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
        */
       public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
           try {
               final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);
   
               log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
               final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(docId));
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
           final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                              + "FROM history(VehicleRegistration, `%s`) "
                                              + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
           ConnectToLedger.getDriver().execute(txn -> {
               final String vin = SampleData.VEHICLES.get(0).getVin();
               previousPrimaryOwners(txn, vin, query);
           });
           log.info("Successfully queried history.");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonValue;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   import java.io.IOException;
   import java.time.Instant;
   import java.time.temporal.ChronoUnit;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Query a table's history for a particular set of documents.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class QueryHistory {
       public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
       private static final int THREE_MONTHS = 90;
   
       private QueryHistory() { }
   
       /**
        * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              VIN to find previous primary owners for.
        * @param query
        *              The query to find previous primary owners.
        * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
        */
       public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
           try {
               final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(docId));
               log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
               final Result result = txn.execute(query, parameters);
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
           final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                              + "FROM history(VehicleRegistration, `%s`) "
                                              + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
           ConnectToLedger.getDriver().execute(txn -> {
               final String vin = SampleData.VEHICLES.get(0).getVin();
               previousPrimaryOwners(txn, vin, query);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Successfully queried history.");
       }
   }
   ```

------
**참고**  
다음 구문에 내장된 [기록 함수](working.history.md#working.history.function)를 쿼리하여 문서의 개정 기록을 볼 수 있습니다  

     ```
     SELECT * FROM history( table_name [, `start-time` [, `end-time` ] ] ) AS h
     [ WHERE h.metadata.id = 'id' ]
     ```
*시작 시간*과 *종료 시간*은 모두 선택 사항입니다. 이 값은 백틱(``...``)으로 표시할 수 있는 Amazon Ion 리터럴 값입니다. 자세한 내용은 [Amazon QLDB에서 PartiQL을 사용한 Ion 쿼리](ql-reference.query.md) 섹션을 참조하세요.
가장 좋은 방법은 날짜 범위(*시작 시간* 및 *종료 시간*)와 문서 ID(`metadata.id`)를 모두 사용하여 기록 쿼리를 한정하는 것입니다. QLDB는 트랜잭션에서 `SELECT` 쿼리를 처리하며, 이 쿼리에는 [트랜잭션 시간 초과 제한](limits.md#limits.fixed)이 적용됩니다.  
QLDB 기록은 문서 ID로 인덱싱되며, 이번에는 추가 기록 인덱스를 만들 수 없습니다. 시작 시간과 종료 시간을 포함하는 기록 쿼리는 날짜 범위 한정이라는 이점을 얻습니다.

1. `QueryHistory.java` 프로그램을 컴파일하고 실행하여 VIN `1N4AL11D75C109151`으로 `VehicleRegistration` 문서의 개정 기록을 쿼리합니다.

`vehicle-registration` 원장의 문서 개정을 암호화 방식으로 검증하려면 [7단계: 원장에 있는 문서 검증](getting-started.java.step-7.md)으로 진행하세요.

# 7단계: 원장에 있는 문서 검증
<a name="getting-started.java.step-7"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB를 사용하면 SHA-256 암호화 해싱을 사용하여 원장 저널에 있는 문서의 무결성을 효율적으로 검증할 수 있습니다. QLDB에서 검증 및 암호화 해싱이 작동하는 방식에 대한 자세한 내용은 [Amazon QLDB에서의 데이터 확인](verification.md)을 참조하세요.

이 단계에서는 `vehicle-registration` 원장의 `VehicleRegistration` 테이블에 있는 문서 개정을 검증합니다. 먼저 다이제스트를 요청합니다. 다이제스트는 출력 파일로 반환되며 원장의 전체 변경 내역에 대한 서명 역할을 합니다. 그런 다음 해당 다이제스트와 관련된 개정 증거를 요청합니다. 이 증거를 사용하면 모든 유효성 검사를 통과한 경우 개정 내용의 무결성을 확인할 수 있습니다.

**문서 개정을 검증하려면**

1. 검증에 필요한 QLDB 객체와 Ion 및 문자열 값에 대한 도우미 메서드가 포함된 유틸리티 클래스를 나타내는 다음 `.java` 파일을 검토하세요.

   1. `BlockAddress.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import java.util.Objects;
      
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      /**
       * Represents the BlockAddress field of a QLDB document.
       */
      public final class BlockAddress {
      
          private static final Logger log = LoggerFactory.getLogger(BlockAddress.class);
      
          private final String strandId;
          private final long sequenceNo;
      
          @JsonCreator
          public BlockAddress(@JsonProperty("strandId") final String strandId,
                              @JsonProperty("sequenceNo") final long sequenceNo) {
              this.strandId = strandId;
              this.sequenceNo = sequenceNo;
          }
      
          public long getSequenceNo() {
              return sequenceNo;
          }
      
          public String getStrandId() {
              return strandId;
          }
      
          @Override
          public String toString() {
              return "BlockAddress{"
                      + "strandId='" + strandId + '\''
                      + ", sequenceNo=" + sequenceNo
                      + '}';
          }
      
          @Override
          public boolean equals(final Object o) {
              if (this == o) {
                  return true;
              }
              if (o == null || getClass() != o.getClass()) {
                  return false;
              }
              BlockAddress that = (BlockAddress) o;
              return sequenceNo == that.sequenceNo
                      && strandId.equals(that.strandId);
          }
      
          @Override
          public int hashCode() {
              // CHECKSTYLE:OFF - Disabling as we are generating a hashCode of multiple properties.
              return Objects.hash(strandId, sequenceNo);
              // CHECKSTYLE:ON
          }
      }
      ```

   1. `Proof.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonReader;
      import com.amazon.ion.IonSystem;
      import com.amazon.ion.system.IonSystemBuilder;
      import com.amazonaws.services.qldb.model.GetRevisionRequest;
      import com.amazonaws.services.qldb.model.GetRevisionResult;
      
      import java.util.ArrayList;
      import java.util.List;
      
      /**
       * A Java representation of the {@link Proof} object.
       * Returned from the {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision(GetRevisionRequest)} api.
       */
      public final class Proof {
          private static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
      
          private List<byte[]> internalHashes;
      
          public Proof(final List<byte[]> internalHashes) {
              this.internalHashes = internalHashes;
          }
      
          public List<byte[]> getInternalHashes() {
              return internalHashes;
          }
      
          /**
           * Decodes a {@link Proof} from an ion text String. This ion text is returned in
           * a {@link GetRevisionResult#getProof()}
           *
           * @param ionText
           *              The ion text representing a {@link Proof} object.
           * @return {@link JournalBlock} parsed from the ion text.
           * @throws IllegalStateException if failed to parse the {@link Proof} object from the given ion text.
           */
          public static Proof fromBlob(final String ionText) {
              try {
                  IonReader reader = SYSTEM.newReader(ionText);
                  List<byte[]> list = new ArrayList<>();
                  reader.next();
                  reader.stepIn();
                  while (reader.next() != null) {
                      list.add(reader.newBytes());
                  }
                  return new Proof(list);
              } catch (Exception e) {
                  throw new IllegalStateException("Failed to parse a Proof from byte array");
              }
          }
      }
      ```

   1. `QldbIonUtils.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonReader;
      import com.amazon.ion.IonValue;
      import com.amazon.ionhash.IonHashReader;
      import com.amazon.ionhash.IonHashReaderBuilder;
      import com.amazon.ionhash.MessageDigestIonHasherProvider;
      import software.amazon.qldb.tutorial.Constants;
      
      public class QldbIonUtils {
      
          private static MessageDigestIonHasherProvider ionHasherProvider = new MessageDigestIonHasherProvider("SHA-256");
      
          private QldbIonUtils() {}
      
          /**
           * Builds a hash value from the given {@link IonValue}.
           *
           * @param ionValue
           *              The {@link IonValue} to hash.
           * @return a byte array representing the hash value.
           */
          public static byte[] hashIonValue(final IonValue ionValue) {
              IonReader reader = Constants.SYSTEM.newReader(ionValue);
              IonHashReader hashReader = IonHashReaderBuilder.standard()
                      .withHasherProvider(ionHasherProvider)
                      .withReader(reader)
                      .build();
              while (hashReader.next() != null) {  }
              return hashReader.digest();
          }
      
      }
      ```

   1. `QldbStringUtils.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonWriter;
      import com.amazon.ion.system.IonReaderBuilder;
      import com.amazon.ion.system.IonTextWriterBuilder;
      import com.amazonaws.services.qldb.model.GetBlockResult;
      import com.amazonaws.services.qldb.model.GetDigestResult;
      import com.amazonaws.services.qldb.model.ValueHolder;
      
      import java.io.IOException;
      
      /**
       * Helper methods to pretty-print certain QLDB response types.
       */
      public class QldbStringUtils {
      
          private QldbStringUtils() {}
      
          /**
           * Returns the string representation of a given {@link ValueHolder}.
           * Adapted from the AWS SDK autogenerated {@code toString()} method, with sensitive values un-redacted.
           * Additionally, this method pretty-prints any IonText included in the {@link ValueHolder}.
           *
           * @param valueHolder the {@link ValueHolder} to convert to a String.
           * @return the String representation of the supplied {@link ValueHolder}.
           */
          public static String toUnredactedString(ValueHolder valueHolder) {
              StringBuilder sb = new StringBuilder();
              sb.append("{");
              if (valueHolder.getIonText() != null) {
      
                  sb.append("IonText: ");
                  IonWriter prettyWriter = IonTextWriterBuilder.pretty().build(sb);
                  try {
                      prettyWriter.writeValues(IonReaderBuilder.standard().build(valueHolder.getIonText()));
                  } catch (IOException ioe) {
                      sb.append("**Exception while printing this IonText**");
                  }
              }
      
              sb.append("}");
              return sb.toString();
          }
      
          /**
           * Returns the string representation of a given {@link GetBlockResult}.
           * Adapted from the AWS SDK autogenerated {@code toString()} method, with sensitive values un-redacted.
           *
           * @param getBlockResult the {@link GetBlockResult} to convert to a String.
           * @return the String representation of the supplied {@link GetBlockResult}.
           */
          public static String toUnredactedString(GetBlockResult getBlockResult) {
              StringBuilder sb = new StringBuilder();
              sb.append("{");
              if (getBlockResult.getBlock() != null) {
                  sb.append("Block: ").append(toUnredactedString(getBlockResult.getBlock())).append(",");
              }
      
              if (getBlockResult.getProof() != null) {
                  sb.append("Proof: ").append(toUnredactedString(getBlockResult.getProof()));
              }
      
              sb.append("}");
              return sb.toString();
          }
      
          /**
           * Returns the string representation of a given {@link GetDigestResult}.
           * Adapted from the AWS SDK autogenerated {@code toString()} method, with sensitive values un-redacted.
           *
           * @param getDigestResult the {@link GetDigestResult} to convert to a String.
           * @return the String representation of the supplied {@link GetDigestResult}.
           */
          public static String toUnredactedString(GetDigestResult getDigestResult) {
              StringBuilder sb = new StringBuilder();
              sb.append("{");
              if (getDigestResult.getDigest() != null) {
                  sb.append("Digest: ").append(getDigestResult.getDigest()).append(",");
              }
      
              if (getDigestResult.getDigestTipAddress() != null) {
                  sb.append("DigestTipAddress: ").append(toUnredactedString(getDigestResult.getDigestTipAddress()));
              }
      
              sb.append("}");
              return sb.toString();
          }
      }
      ```

   1. `Verifier.java`

------
#### [ 2.x ]

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial;
      
      import java.nio.ByteBuffer;
      import java.nio.charset.StandardCharsets;
      import java.security.MessageDigest;
      import java.security.NoSuchAlgorithmException;
      import java.util.ArrayList;
      import java.util.Arrays;
      import java.util.Comparator;
      import java.util.Iterator;
      import java.util.List;
      import java.util.concurrent.ThreadLocalRandom;
      
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      
      import com.amazonaws.util.Base64;
      
      import software.amazon.qldb.tutorial.qldb.Proof;
      
      /**
       * Encapsulates the logic to verify the integrity of revisions or blocks in a QLDB ledger.
       *
       * The main entry point is {@link #verify(byte[], byte[], String)}.
       *
       * This code expects that you have AWS credentials setup per:
       * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
       */
      public final class Verifier {
          public static final Logger log = LoggerFactory.getLogger(Verifier.class);
          private static final int HASH_LENGTH = 32;
          private static final int UPPER_BOUND = 8;
      
          /**
           * Compares two hashes by their <em>signed</em> byte values in little-endian order.
           */
          private static Comparator<byte[]> hashComparator = (h1, h2) -> {
              if (h1.length != HASH_LENGTH || h2.length != HASH_LENGTH) {
                  throw new IllegalArgumentException("Invalid hash.");
              }
              for (int i = h1.length - 1; i >= 0; i--) {
                  int byteEqual = Byte.compare(h1[i], h2[i]);
                  if (byteEqual != 0) {
                      return byteEqual;
                  }
              }
      
              return 0;
          };
      
          private Verifier() { }
      
          /**
           * Verify the integrity of a document with respect to a QLDB ledger digest.
           *
           * The verification algorithm includes the following steps:
           *
           * 1. {@link #buildCandidateDigest(Proof, byte[])} build the candidate digest from the internal hashes
           * in the {@link Proof}.
           * 2. Check that the {@code candidateLedgerDigest} is equal to the {@code ledgerDigest}.
           *
           * @param documentHash
           *              The hash of the document to be verified.
           * @param digest
           *              The QLDB ledger digest. This digest should have been retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getDigest}
           * @param proofBlob
           *              The ion encoded bytes representing the {@link Proof} associated with the supplied
           *              {@code digestTipAddress} and {@code address} retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @return {@code true} if the record is verified or {@code false} if it is not verified.
           */
          public static boolean verify(
                  final byte[] documentHash,
                  final byte[] digest,
                  final String proofBlob
          ) {
              Proof proof = Proof.fromBlob(proofBlob);
      
              byte[] candidateDigest = buildCandidateDigest(proof, documentHash);
      
              return Arrays.equals(digest, candidateDigest);
          }
      
          /**
           * Build the candidate digest representing the entire ledger from the internal hashes of the {@link Proof}.
           *
           * @param proof
           *              A Java representation of {@link Proof}
           *              returned from {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @param leafHash
           *              Leaf hash to build the candidate digest with.
           * @return a byte array of the candidate digest.
           */
          private static byte[] buildCandidateDigest(final Proof proof, final byte[] leafHash) {
              return calculateRootHashFromInternalHashes(proof.getInternalHashes(), leafHash);
          }
      
          /**
           * Get a new instance of {@link MessageDigest} using the SHA-256 algorithm.
           *
           * @return an instance of {@link MessageDigest}.
           * @throws IllegalStateException if the algorithm is not available on the current JVM.
           */
          static MessageDigest newMessageDigest() {
              try {
                  return MessageDigest.getInstance("SHA-256");
              } catch (NoSuchAlgorithmException e) {
                  log.error("Failed to create SHA-256 MessageDigest", e);
                  throw new IllegalStateException("SHA-256 message digest is unavailable", e);
              }
          }
      
          /**
           * Takes two hashes, sorts them, concatenates them, and then returns the
           * hash of the concatenated array.
           *
           * @param h1
           *              Byte array containing one of the hashes to compare.
           * @param h2
           *              Byte array containing one of the hashes to compare.
           * @return the concatenated array of hashes.
           */
          public static byte[] dot(final byte[] h1, final byte[] h2) {
              if (h1.length == 0) {
                  return h2;
              }
              if (h2.length == 0) {
                  return h1;
              }
              byte[] concatenated = new byte[h1.length + h2.length];
              if (hashComparator.compare(h1, h2) < 0) {
                  System.arraycopy(h1, 0, concatenated, 0, h1.length);
                  System.arraycopy(h2, 0, concatenated, h1.length, h2.length);
              } else {
                  System.arraycopy(h2, 0, concatenated, 0, h2.length);
                  System.arraycopy(h1, 0, concatenated, h2.length, h1.length);
              }
              MessageDigest messageDigest = newMessageDigest();
              messageDigest.update(concatenated);
      
              return messageDigest.digest();
          }
      
          /**
           * Starting with the provided {@code leafHash} combined with the provided {@code internalHashes}
           * pairwise until only the root hash remains.
           *
           * @param internalHashes
           *              Internal hashes of Merkle tree.
           * @param leafHash
           *              Leaf hashes of Merkle tree.
           * @return the root hash.
           */
          private static byte[] calculateRootHashFromInternalHashes(final List<byte[]> internalHashes, final byte[] leafHash) {
              return internalHashes.stream().reduce(leafHash, Verifier::dot);
          }
      
          /**
           * Flip a single random bit in the given byte array. This method is used to demonstrate
           * QLDB's verification features.
           *
           * @param original
           *              The original byte array.
           * @return the altered byte array with a single random bit changed.
           */
          public static byte[] flipRandomBit(final byte[] original) {
              if (original.length == 0) {
                  throw new IllegalArgumentException("Array cannot be empty!");
              }
              int alteredPosition = ThreadLocalRandom.current().nextInt(original.length);
              int b = ThreadLocalRandom.current().nextInt(UPPER_BOUND);
              byte[] altered = new byte[original.length];
              System.arraycopy(original, 0, altered, 0, original.length);
              altered[alteredPosition] = (byte) (altered[alteredPosition] ^ (1 << b));
              return altered;
          }
      
          public static String toBase64(byte[] arr) {
              return new String(Base64.encode(arr), StandardCharsets.UTF_8);
          }
      
          /**
           * Convert a {@link ByteBuffer} into byte array.
           *
           * @param buffer
           *              The {@link ByteBuffer} to convert.
           * @return the converted byte array.
           */
          public static byte[] convertByteBufferToByteArray(final ByteBuffer buffer) {
              byte[] arr = new byte[buffer.remaining()];
              buffer.get(arr);
              return arr;
          }
      
          /**
           * Calculates the root hash from a list of hashes that represent the base of a Merkle tree.
           *
           * @param hashes
           *              The list of byte arrays representing hashes making up base of a Merkle tree.
           * @return a byte array that is the root hash of the given list of hashes.
           */
          public static byte[] calculateMerkleTreeRootHash(List<byte[]> hashes) {
              if (hashes.isEmpty()) {
                  return new byte[0];
              }
      
              List<byte[]> remaining = combineLeafHashes(hashes);
              while (remaining.size() > 1) {
                  remaining = combineLeafHashes(remaining);
              }
              return remaining.get(0);
          }
      
          private static List<byte[]> combineLeafHashes(List<byte[]> hashes) {
              List<byte[]> combinedHashes = new ArrayList<>();
              Iterator<byte[]> it = hashes.stream().iterator();
      
              while (it.hasNext()) {
                  byte[] left = it.next();
                  if (it.hasNext()) {
                      byte[] right = it.next();
                      byte[] combined = dot(left, right);
                      combinedHashes.add(combined);
                  } else {
                      combinedHashes.add(left);
                  }
              }
      
              return combinedHashes;
          }
      }
      ```

------
#### [ 1.x ]

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial;
      
      import com.amazonaws.util.Base64;
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      import software.amazon.qldb.tutorial.qldb.Proof;
      
      import java.nio.ByteBuffer;
      import java.nio.charset.StandardCharsets;
      import java.security.MessageDigest;
      import java.security.NoSuchAlgorithmException;
      import java.util.*;
      import java.util.concurrent.ThreadLocalRandom;
      
      /**
       * Encapsulates the logic to verify the integrity of revisions or blocks in a QLDB ledger.
       *
       * The main entry point is {@link #verify(byte[], byte[], String)}.
       *
       * This code expects that you have AWS credentials setup per:
       * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
       */
      public final class Verifier {
          public static final Logger log = LoggerFactory.getLogger(Verifier.class);
          private static final int HASH_LENGTH = 32;
          private static final int UPPER_BOUND = 8;
      
          /**
           * Compares two hashes by their <em>signed</em> byte values in little-endian order.
           */
          private static Comparator<byte[]> hashComparator = (h1, h2) -> {
              if (h1.length != HASH_LENGTH || h2.length != HASH_LENGTH) {
                  throw new IllegalArgumentException("Invalid hash.");
              }
              for (int i = h1.length - 1; i >= 0; i--) {
                  int byteEqual = Byte.compare(h1[i], h2[i]);
                  if (byteEqual != 0) {
                      return byteEqual;
                  }
              }
      
              return 0;
          };
      
          private Verifier() { }
      
          /**
           * Verify the integrity of a document with respect to a QLDB ledger digest.
           *
           * The verification algorithm includes the following steps:
           *
           * 1. {@link #buildCandidateDigest(Proof, byte[])} build the candidate digest from the internal hashes
           * in the {@link Proof}.
           * 2. Check that the {@code candidateLedgerDigest} is equal to the {@code ledgerDigest}.
           *
           * @param documentHash
           *              The hash of the document to be verified.
           * @param digest
           *              The QLDB ledger digest. This digest should have been retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getDigest}
           * @param proofBlob
           *              The ion encoded bytes representing the {@link Proof} associated with the supplied
           *              {@code digestTipAddress} and {@code address} retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @return {@code true} if the record is verified or {@code false} if it is not verified.
           */
          public static boolean verify(
                  final byte[] documentHash,
                  final byte[] digest,
                  final String proofBlob
          ) {
              Proof proof = Proof.fromBlob(proofBlob);
      
              byte[] candidateDigest = buildCandidateDigest(proof, documentHash);
      
              return Arrays.equals(digest, candidateDigest);
          }
      
          /**
           * Build the candidate digest representing the entire ledger from the internal hashes of the {@link Proof}.
           *
           * @param proof
           *              A Java representation of {@link Proof}
           *              returned from {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @param leafHash
           *              Leaf hash to build the candidate digest with.
           * @return a byte array of the candidate digest.
           */
          private static byte[] buildCandidateDigest(final Proof proof, final byte[] leafHash) {
              return calculateRootHashFromInternalHashes(proof.getInternalHashes(), leafHash);
          }
      
          /**
           * Get a new instance of {@link MessageDigest} using the SHA-256 algorithm.
           *
           * @return an instance of {@link MessageDigest}.
           * @throws IllegalStateException if the algorithm is not available on the current JVM.
           */
          static MessageDigest newMessageDigest() {
              try {
                  return MessageDigest.getInstance("SHA-256");
              } catch (NoSuchAlgorithmException e) {
                  log.error("Failed to create SHA-256 MessageDigest", e);
                  throw new IllegalStateException("SHA-256 message digest is unavailable", e);
              }
          }
      
          /**
           * Takes two hashes, sorts them, concatenates them, and then returns the
           * hash of the concatenated array.
           *
           * @param h1
           *              Byte array containing one of the hashes to compare.
           * @param h2
           *              Byte array containing one of the hashes to compare.
           * @return the concatenated array of hashes.
           */
          public static byte[] dot(final byte[] h1, final byte[] h2) {
              if (h1.length == 0) {
                  return h2;
              }
              if (h2.length == 0) {
                  return h1;
              }
              byte[] concatenated = new byte[h1.length + h2.length];
              if (hashComparator.compare(h1, h2) < 0) {
                  System.arraycopy(h1, 0, concatenated, 0, h1.length);
                  System.arraycopy(h2, 0, concatenated, h1.length, h2.length);
              } else {
                  System.arraycopy(h2, 0, concatenated, 0, h2.length);
                  System.arraycopy(h1, 0, concatenated, h2.length, h1.length);
              }
              MessageDigest messageDigest = newMessageDigest();
              messageDigest.update(concatenated);
      
              return messageDigest.digest();
          }
      
          /**
           * Starting with the provided {@code leafHash} combined with the provided {@code internalHashes}
           * pairwise until only the root hash remains.
           *
           * @param internalHashes
           *              Internal hashes of Merkle tree.
           * @param leafHash
           *              Leaf hashes of Merkle tree.
           * @return the root hash.
           */
          private static byte[] calculateRootHashFromInternalHashes(final List<byte[]> internalHashes, final byte[] leafHash) {
              return internalHashes.stream().reduce(leafHash, Verifier::dot);
          }
      
          /**
           * Flip a single random bit in the given byte array. This method is used to demonstrate
           * QLDB's verification features.
           *
           * @param original
           *              The original byte array.
           * @return the altered byte array with a single random bit changed.
           */
          public static byte[] flipRandomBit(final byte[] original) {
              if (original.length == 0) {
                  throw new IllegalArgumentException("Array cannot be empty!");
              }
              int alteredPosition = ThreadLocalRandom.current().nextInt(original.length);
              int b = ThreadLocalRandom.current().nextInt(UPPER_BOUND);
              byte[] altered = new byte[original.length];
              System.arraycopy(original, 0, altered, 0, original.length);
              altered[alteredPosition] = (byte) (altered[alteredPosition] ^ (1 << b));
              return altered;
          }
      
          public static String toBase64(byte[] arr) {
              return new String(Base64.encode(arr), StandardCharsets.UTF_8);
          }
      
          /**
           * Convert a {@link ByteBuffer} into byte array.
           *
           * @param buffer
           *              The {@link ByteBuffer} to convert.
           * @return the converted byte array.
           */
          public static byte[] convertByteBufferToByteArray(final ByteBuffer buffer) {
              byte[] arr = new byte[buffer.remaining()];
              buffer.get(arr);
              return arr;
          }
      
          /**
           * Calculates the root hash from a list of hashes that represent the base of a Merkle tree.
           *
           * @param hashes
           *              The list of byte arrays representing hashes making up base of a Merkle tree.
           * @return a byte array that is the root hash of the given list of hashes.
           */
          public static byte[] calculateMerkleTreeRootHash(List<byte[]> hashes) {
              if (hashes.isEmpty()) {
                  return new byte[0];
              }
      
              List<byte[]> remaining = combineLeafHashes(hashes);
              while (remaining.size() > 1) {
                  remaining = combineLeafHashes(remaining);
              }
              return remaining.get(0);
          }
      
          private static List<byte[]> combineLeafHashes(List<byte[]> hashes) {
              List<byte[]> combinedHashes = new ArrayList<>();
              Iterator<byte[]> it = hashes.stream().iterator();
      
              while (it.hasNext()) {
                  byte[] left = it.next();
                  if (it.hasNext()) {
                      byte[] right = it.next();
                      byte[] combined = dot(left, right);
                      combinedHashes.add(combined);
                  } else {
                      combinedHashes.add(left);
                  }
              }
      
              return combinedHashes;
          }
      }
      ```

------

1. 두 개의 `.java` 파일(`GetDigest.java` 및 `GetRevision.java`)을 사용하여 다음 단계를 수행하세요.
   + `vehicle-registration` 원장에 새 다이제스트를 요청하세요.
   + `VehicleRegistration` 테이블에 있는 문서의 각 개정에 대한 증거를 요청합니다.
   + 반환된 다이제스트와 증거를 사용하여 다이제스트를 다시 계산하여 개정 내용을 검증합니다.

   `GetDigest.java` 프로그램에는 다음 코드가 포함되어 있습니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.GetDigestRequest;
   import com.amazonaws.services.qldb.model.GetDigestResult;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.tutorial.qldb.QldbStringUtils;
   
   /**
    * This is an example for retrieving the digest of a particular ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class GetDigest {
       public static final Logger log = LoggerFactory.getLogger(GetDigest.class);
       public static AmazonQLDB client = CreateLedger.getClient();
   
       private GetDigest() { }
   
       /**
        * Calls {@link #getDigest(String)} for a ledger.
        *
        * @param args
        *              Arbitrary command-line arguments.
        * @throws Exception if failed to get a ledger digest.
        */
       public static void main(final String... args) throws Exception {
           try {
   
               getDigest(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to get a ledger digest!", e);
               throw e;
           }
       }
   
       /**
        * Get the digest for the specified ledger.
        *
        * @param ledgerName
        *              The ledger to get digest from.
        * @return {@link GetDigestResult}.
        */
       public static GetDigestResult getDigest(final String ledgerName) {
           log.info("Let's get the current digest of the ledger named {}.", ledgerName);
           GetDigestRequest request = new GetDigestRequest()
                   .withName(ledgerName);
           GetDigestResult result = client.getDigest(request);
           log.info("Success. LedgerDigest: {}.", QldbStringUtils.toUnredactedString(result));
           return result;
       }
   }
   ```
**참고**  
`getDigest` 메서드를 사용하여 원장에 있는 저널의 현재 *팁*을 포함하는 다이제스트를 요청합니다. 저널 팁은 QLDB가 요청을 수신한 시점을 기준으로 가장 최근에 커밋된 블록을 나타냅니다.

   `GetRevision.java` 프로그램에는 다음 코드가 포함되어 있습니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonSystem;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.IonWriter;
   import com.amazon.ion.system.IonReaderBuilder;
   import com.amazon.ion.system.IonSystemBuilder;
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.GetDigestResult;
   import com.amazonaws.services.qldb.model.GetRevisionRequest;
   import com.amazonaws.services.qldb.model.GetRevisionResult;
   import com.amazonaws.services.qldb.model.ValueHolder;
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbDriver;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.qldb.BlockAddress;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   import software.amazon.qldb.tutorial.qldb.QldbStringUtils;
   
   /**
    * Verify the integrity of a document revision in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class GetRevision {
       public static final Logger log = LoggerFactory.getLogger(GetRevision.class);
       public static AmazonQLDB client = CreateLedger.getClient();
       private static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
   
       private GetRevision() { }
   
       public static void main(String... args) throws Exception {
   
           final String vin = SampleData.REGISTRATIONS.get(0).getVin();
   
   
           verifyRegistration(ConnectToLedger.getDriver(), Constants.LEDGER_NAME, vin);
       }
   
       /**
        * Verify each version of the registration for the given VIN.
        *
        * @param driver
        *              A QLDB driver.
        * @param ledgerName
        *              The ledger to get digest from.
        * @param vin
        *              VIN to query the revision history of a specific registration with.
        * @throws Exception if failed to verify digests.
        * @throws AssertionError if document revision verification failed.
        */
       public static void verifyRegistration(final QldbDriver driver, final String ledgerName, final String vin)
               throws Exception {
           log.info(String.format("Let's verify the registration with VIN=%s, in ledger=%s.", vin, ledgerName));
   
           try {
               log.info("First, let's get a digest.");
               GetDigestResult digestResult = GetDigest.getDigest(ledgerName);
   
               ValueHolder digestTipAddress = digestResult.getDigestTipAddress();
               byte[] digestBytes = Verifier.convertByteBufferToByteArray(digestResult.getDigest());
   
               log.info("Got a ledger digest. Digest end address={}, digest={}.",
                   QldbStringUtils.toUnredactedString(digestTipAddress),
                   Verifier.toBase64(digestBytes));
   
               log.info(String.format("Next, let's query the registration with VIN=%s. "
                       + "Then we can verify each version of the registration.", vin));
               List<IonStruct> documentsWithMetadataList = new ArrayList<>();
               driver.execute(txn -> {
                   documentsWithMetadataList.addAll(queryRegistrationsByVin(txn, vin));
               });
               log.info("Registrations queried successfully!");
   
               log.info(String.format("Found %s revisions of the registration with VIN=%s.",
                       documentsWithMetadataList.size(), vin));
   
               for (IonStruct ionStruct : documentsWithMetadataList) {
   
                   QldbRevision document = QldbRevision.fromIon(ionStruct);
                   log.info(String.format("Let's verify the document: %s", document));
   
                   log.info("Let's get a proof for the document.");
                   GetRevisionResult proofResult = getRevision(
                           ledgerName,
                           document.getMetadata().getId(),
                           digestTipAddress,
                           document.getBlockAddress()
                   );
   
                   final IonValue proof = Constants.MAPPER.writeValueAsIonValue(proofResult.getProof());
                   final IonReader reader = IonReaderBuilder.standard().build(proof);
                   reader.next();
                   ByteArrayOutputStream baos = new ByteArrayOutputStream();
                   IonWriter writer = SYSTEM.newBinaryWriter(baos);
                   writer.writeValue(reader);
                   writer.close();
                   baos.flush();
                   baos.close();
                   byte[] byteProof = baos.toByteArray();
   
                   log.info(String.format("Got back a proof: %s", Verifier.toBase64(byteProof)));
   
                   boolean verified = Verifier.verify(
                           document.getHash(),
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (!verified) {
                       throw new AssertionError("Document revision is not verified!");
                   } else {
                       log.info("Success! The document is verified");
                   }
   
                   byte[] alteredDigest = Verifier.flipRandomBit(digestBytes);
                   log.info(String.format("Flipping one bit in the digest and assert that the document is NOT verified. "
                           + "The altered digest is: %s", Verifier.toBase64(alteredDigest)));
                   verified = Verifier.verify(
                           document.getHash(),
                           alteredDigest,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected document to not be verified against altered digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the digest causes verification to fail.");
                   }
   
                   byte[] alteredDocumentHash = Verifier.flipRandomBit(document.getHash());
                   log.info(String.format("Flipping one bit in the document's hash and assert that it is NOT verified. "
                           + "The altered document hash is: %s.", Verifier.toBase64(alteredDocumentHash)));
                   verified = Verifier.verify(
                           alteredDocumentHash,
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected altered document hash to not be verified against digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the document hash causes verification to fail.");
                   }
               }
   
           } catch (Exception e) {
               log.error("Failed to verify digests.", e);
               throw e;
           }
   
           log.info(String.format("Finished verifying the registration with VIN=%s in ledger=%s.", vin, ledgerName));
       }
   
       /**
        * Get the revision of a particular document specified by the given document ID and block address.
        *
        * @param ledgerName
        *              Name of the ledger containing the document.
        * @param documentId
        *              Unique ID for the document to be verified, contained in the committed view of the document.
        * @param digestTipAddress
        *              The latest block location covered by the digest.
        * @param blockAddress
        *              The location of the block to request.
        * @return the requested revision.
        */
       public static GetRevisionResult getRevision(final String ledgerName, final String documentId,
                                                   final ValueHolder digestTipAddress, final BlockAddress blockAddress) {
           try {
               GetRevisionRequest request = new GetRevisionRequest()
                       .withName(ledgerName)
                       .withDigestTipAddress(digestTipAddress)
                       .withBlockAddress(new ValueHolder().withIonText(Constants.MAPPER.writeValueAsIonValue(blockAddress)
                               .toString()))
                       .withDocumentId(documentId);
               return client.getRevision(request);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Query the registration history for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              The unique VIN to query.
        * @return a list of {@link IonStruct} representing the registration history.
        * @throws IllegalStateException if failed to convert parameters into {@link IonValue}
        */
       public static List<IonStruct> queryRegistrationsByVin(final TransactionExecutor txn, final String vin) {
           log.info(String.format("Let's query the 'VehicleRegistration' table for VIN: %s...", vin));
           log.info("Let's query the 'VehicleRegistration' table for VIN: {}...", vin);
           final String query = String.format("SELECT * FROM _ql_committed_%s WHERE data.VIN = ?",
                   Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               List<IonStruct> list = ScanTable.toIonStructs(result);
               log.info(String.format("Found %d document(s)!", list.size()));
               return list;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.IonWriter;
   import com.amazon.ion.system.IonReaderBuilder;
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.GetDigestResult;
   import com.amazonaws.services.qldb.model.GetRevisionRequest;
   import com.amazonaws.services.qldb.model.GetRevisionResult;
   import com.amazonaws.services.qldb.model.ValueHolder;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.qldb.BlockAddress;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   import software.amazon.qldb.tutorial.qldb.QldbStringUtils;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Verify the integrity of a document revision in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class GetRevision {
       public static final Logger log = LoggerFactory.getLogger(GetRevision.class);
       public static AmazonQLDB client = CreateLedger.getClient();
   
       private GetRevision() { }
   
       public static void main(String... args) throws Exception {
   
           final String vin = SampleData.REGISTRATIONS.get(0).getVin();
   
           try (QldbSession qldbSession = ConnectToLedger.createQldbSession()) {
               verifyRegistration(qldbSession, Constants.LEDGER_NAME, vin);
           }
       }
   
       /**
        * Verify each version of the registration for the given VIN.
        *
        * @param qldbSession
        *              A QLDB session.
        * @param ledgerName
        *              The ledger to get digest from.
        * @param vin
        *              VIN to query the revision history of a specific registration with.
        * @throws Exception if failed to verify digests.
        * @throws AssertionError if document revision verification failed.
        */
       public static void verifyRegistration(final QldbSession qldbSession, final String ledgerName, final String vin)
               throws Exception {
           log.info(String.format("Let's verify the registration with VIN=%s, in ledger=%s.", vin, ledgerName));
   
           try {
               log.info("First, let's get a digest.");
               GetDigestResult digestResult = GetDigest.getDigest(ledgerName);
   
               ValueHolder digestTipAddress = digestResult.getDigestTipAddress();
               byte[] digestBytes = Verifier.convertByteBufferToByteArray(digestResult.getDigest());
   
               log.info("Got a ledger digest. Digest end address={}, digest={}.",
                   QldbStringUtils.toUnredactedString(digestTipAddress),
                   Verifier.toBase64(digestBytes));
   
               log.info(String.format("Next, let's query the registration with VIN=%s. "
                       + "Then we can verify each version of the registration.", vin));
               List<IonStruct> documentsWithMetadataList = new ArrayList<>();
               qldbSession.execute(txn -> {
                   documentsWithMetadataList.addAll(queryRegistrationsByVin(txn, vin));
               }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
               log.info("Registrations queried successfully!");
   
               log.info(String.format("Found %s revisions of the registration with VIN=%s.",
                       documentsWithMetadataList.size(), vin));
   
               for (IonStruct ionStruct : documentsWithMetadataList) {
   
                   QldbRevision document = QldbRevision.fromIon(ionStruct);
                   log.info(String.format("Let's verify the document: %s", document));
   
                   log.info("Let's get a proof for the document.");
                   GetRevisionResult proofResult = getRevision(
                           ledgerName,
                           document.getMetadata().getId(),
                           digestTipAddress,
                           document.getBlockAddress()
                   );
   
                   final IonValue proof = Constants.MAPPER.writeValueAsIonValue(proofResult.getProof());
                   final IonReader reader = IonReaderBuilder.standard().build(proof);
                   reader.next();
                   ByteArrayOutputStream baos = new ByteArrayOutputStream();
                   IonWriter writer = Constants.SYSTEM.newBinaryWriter(baos);
                   writer.writeValue(reader);
                   writer.close();
                   baos.flush();
                   baos.close();
                   byte[] byteProof = baos.toByteArray();
   
                   log.info(String.format("Got back a proof: %s", Verifier.toBase64(byteProof)));
   
                   boolean verified = Verifier.verify(
                           document.getHash(),
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (!verified) {
                       throw new AssertionError("Document revision is not verified!");
                   } else {
                       log.info("Success! The document is verified");
                   }
   
                   byte[] alteredDigest = Verifier.flipRandomBit(digestBytes);
                   log.info(String.format("Flipping one bit in the digest and assert that the document is NOT verified. "
                           + "The altered digest is: %s", Verifier.toBase64(alteredDigest)));
                   verified = Verifier.verify(
                           document.getHash(),
                           alteredDigest,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected document to not be verified against altered digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the digest causes verification to fail.");
                   }
   
                   byte[] alteredDocumentHash = Verifier.flipRandomBit(document.getHash());
                   log.info(String.format("Flipping one bit in the document's hash and assert that it is NOT verified. "
                           + "The altered document hash is: %s.", Verifier.toBase64(alteredDocumentHash)));
                   verified = Verifier.verify(
                           alteredDocumentHash,
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected altered document hash to not be verified against digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the document hash causes verification to fail.");
                   }
               }
   
           } catch (Exception e) {
               log.error("Failed to verify digests.", e);
               throw e;
           }
   
           log.info(String.format("Finished verifying the registration with VIN=%s in ledger=%s.", vin, ledgerName));
       }
   
       /**
        * Get the revision of a particular document specified by the given document ID and block address.
        *
        * @param ledgerName
        *              Name of the ledger containing the document.
        * @param documentId
        *              Unique ID for the document to be verified, contained in the committed view of the document.
        * @param digestTipAddress
        *              The latest block location covered by the digest.
        * @param blockAddress
        *              The location of the block to request.
        * @return the requested revision.
        */
       public static GetRevisionResult getRevision(final String ledgerName, final String documentId,
                                                   final ValueHolder digestTipAddress, final BlockAddress blockAddress) {
           try {
               GetRevisionRequest request = new GetRevisionRequest()
                       .withName(ledgerName)
                       .withDigestTipAddress(digestTipAddress)
                       .withBlockAddress(new ValueHolder().withIonText(Constants.MAPPER.writeValueAsIonValue(blockAddress)
                               .toString()))
                       .withDocumentId(documentId);
               return client.getRevision(request);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Query the registration history for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              The unique VIN to query.
        * @return a list of {@link IonStruct} representing the registration history.
        * @throws IllegalStateException if failed to convert parameters into {@link IonValue}
        */
       public static List<IonStruct> queryRegistrationsByVin(final TransactionExecutor txn, final String vin) {
           log.info(String.format("Let's query the 'VehicleRegistration' table for VIN: %s...", vin));
           log.info("Let's query the 'VehicleRegistration' table for VIN: {}...", vin);
           final String query = String.format("SELECT * FROM _ql_committed_%s WHERE data.VIN = ?",
                   Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               List<IonStruct> list = ScanTable.toIonStructs(result);
               log.info(String.format("Found %d document(s)!", list.size()));
               return list;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   }
   ```

------
**참고**  
`getRevision` 메서드가 지정된 문서 개정에 대한 증거를 반환하면 이 프로그램은 클라이언트 측 API를 사용하여 해당 개정을 검증합니다. 이 API에서 사용하는 알고리즘에 대한 개요는 [증명을 사용하여 다이제스트를 다시 계산하기](verification.results.md#verification.results.recalc) 섹션을 참조하세요.

1. `GetRevision.java` 프로그램을 컴파일하고 실행하여 VIN `1N4AL11D75C109151`으로 `VehicleRegistration` 문서를 암호학적으로 검증합니다.

`vehicle-registration` 원장의 저널 데이터를 내보내고 검증하려면 [8단계: 원장의 저널 데이터 내보내기 및 검증](getting-started.java.step-8.md)로 이동하세요.

# 8단계: 원장의 저널 데이터 내보내기 및 검증
<a name="getting-started.java.step-8"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB에서는 데이터 보존, 분석 및 감사와 같은 다양한 목적으로 원장의 저널 콘텐츠에 액세스할 수 있습니다. 자세한 내용은 [Amazon QLDB에서 저널 데이터 내보내기](export-journal.md) 단원을 참조하십시오.

이 단계에서는 `vehicle-registration` 원장의 [저널 블록](journal-contents.md)을 Amazon S3 버킷으로 내보냅니다. 그런 다음 내보낸 데이터를 사용하여 저널 블록과 각 블록 내 개별 해시 구성 요소 간의 해시 체인을 검증합니다.

사용하는 AWS Identity and Access Management (IAM) 보안 주체 엔터티에는에서 Amazon S3 버킷을 생성할 수 있는 충분한 IAM 권한이 있어야 합니다 AWS 계정. 자세한 내용은 *Amazon S3 사용 설명서*의 [Amazon S3의 정책 및 권한](https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-policy-language-overview.html)을 참조하세요. 또한 QLDB가 Amazon S3 버킷에 객체를 쓸 수 있도록 허용하는 권한 정책이 첨부된 IAM 역할을 생성할 권한이 있어야 합니다. 자세한 내용은 *IAM 사용 설명서*에서 [IAM 리소스에 액세스하는 데 필요한 권한](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_permissions-required.html)을 참조하세요.

**저널 데이터를 내보내고 검증하려면**

1. 저널 블록과 해당 데이터 내용을 나타내는 다음 파일(`JournalBlock.java`)을 검토하세요. 여기에는 블록 해시의 각 개별 구성 요소를 계산하는 방법을 보여주는 `verifyBlockHash()`라는 이름의 메서드가 포함되어 있습니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial.qldb;
   
   import com.fasterxml.jackson.annotation.JsonCreator;
   import com.fasterxml.jackson.annotation.JsonProperty;
   import com.fasterxml.jackson.databind.annotation.JsonSerialize;
   import com.fasterxml.jackson.dataformat.ion.IonTimestampSerializers;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.tutorial.Constants;
   import software.amazon.qldb.tutorial.Verifier;
   
   import java.io.IOException;
   import java.nio.ByteBuffer;
   import java.util.Arrays;
   import java.util.Date;
   import java.util.HashSet;
   import java.util.List;
   import java.util.Set;
   import java.util.stream.Collectors;
   
   import static java.nio.ByteBuffer.wrap;
   
   /**
    * Represents a JournalBlock that was recorded after executing a transaction
    * in the ledger.
    */
   public final class JournalBlock {
       private static final Logger log = LoggerFactory.getLogger(JournalBlock.class);
   
       private BlockAddress blockAddress;
       private String transactionId;
       @JsonSerialize(using = IonTimestampSerializers.IonTimestampJavaDateSerializer.class)
       private Date blockTimestamp;
       private byte[] blockHash;
       private byte[] entriesHash;
       private byte[] previousBlockHash;
       private byte[][] entriesHashList;
       private TransactionInfo transactionInfo;
       private RedactionInfo redactionInfo;
       private List<QldbRevision> revisions;
   
       @JsonCreator
       public JournalBlock(@JsonProperty("blockAddress") final BlockAddress blockAddress,
                           @JsonProperty("transactionId") final String transactionId,
                           @JsonProperty("blockTimestamp") final Date blockTimestamp,
                           @JsonProperty("blockHash") final byte[] blockHash,
                           @JsonProperty("entriesHash") final byte[] entriesHash,
                           @JsonProperty("previousBlockHash") final byte[] previousBlockHash,
                           @JsonProperty("entriesHashList") final byte[][] entriesHashList,
                           @JsonProperty("transactionInfo") final TransactionInfo transactionInfo,
                           @JsonProperty("redactionInfo") final RedactionInfo redactionInfo,
                           @JsonProperty("revisions") final List<QldbRevision> revisions) {
           this.blockAddress = blockAddress;
           this.transactionId = transactionId;
           this.blockTimestamp = blockTimestamp;
           this.blockHash = blockHash;
           this.entriesHash = entriesHash;
           this.previousBlockHash = previousBlockHash;
           this.entriesHashList = entriesHashList;
           this.transactionInfo = transactionInfo;
           this.redactionInfo = redactionInfo;
           this.revisions = revisions;
       }
   
       public BlockAddress getBlockAddress() {
           return blockAddress;
       }
   
       public String getTransactionId() {
           return transactionId;
       }
   
       public Date getBlockTimestamp() {
           return blockTimestamp;
       }
   
       public byte[][] getEntriesHashList() {
           return entriesHashList;
       }
   
       public TransactionInfo getTransactionInfo() {
           return transactionInfo;
       }
   
       public RedactionInfo getRedactionInfo() {
           return redactionInfo;
       }
   
       public List<QldbRevision> getRevisions() {
           return revisions;
       }
   
       public byte[] getEntriesHash() {
           return entriesHash;
       }
   
       public byte[] getBlockHash() {
           return blockHash;
       }
   
       public byte[] getPreviousBlockHash() {
           return previousBlockHash;
       }
   
       @Override
       public String toString() {
           return "JournalBlock{"
                   + "blockAddress=" + blockAddress
                   + ", transactionId='" + transactionId + '\''
                   + ", blockTimestamp=" + blockTimestamp
                   + ", blockHash=" + Arrays.toString(blockHash)
                   + ", entriesHash=" + Arrays.toString(entriesHash)
                   + ", previousBlockHash=" + Arrays.toString(previousBlockHash)
                   + ", entriesHashList=" + Arrays.toString(entriesHashList)
                   + ", transactionInfo=" + transactionInfo
                   + ", redactionInfo=" + redactionInfo
                   + ", revisions=" + revisions
                   + '}';
       }
   
       @Override
       public boolean equals(final Object o) {
           if (this == o) {
               return true;
           }
           if (!(o instanceof JournalBlock)) {
               return false;
           }
   
           final JournalBlock that = (JournalBlock) o;
   
           if (!getBlockAddress().equals(that.getBlockAddress())) {
               return false;
           }
           if (!getTransactionId().equals(that.getTransactionId())) {
               return false;
           }
           if (!getBlockTimestamp().equals(that.getBlockTimestamp())) {
               return false;
           }
           if (!Arrays.equals(getBlockHash(), that.getBlockHash())) {
               return false;
           }
           if (!Arrays.equals(getEntriesHash(), that.getEntriesHash())) {
               return false;
           }
           if (!Arrays.equals(getPreviousBlockHash(), that.getPreviousBlockHash())) {
               return false;
           }
           if (!Arrays.deepEquals(getEntriesHashList(), that.getEntriesHashList())) {
               return false;
           }
           if (!getTransactionInfo().equals(that.getTransactionInfo())) {
               return false;
           }
           if (getRedactionInfo() != null ? !getRedactionInfo().equals(that.getRedactionInfo()) : that.getRedactionInfo() != null) {
               return false;
           }
           return getRevisions() != null ? getRevisions().equals(that.getRevisions()) : that.getRevisions() == null;
       }
   
       @Override
       public int hashCode() {
           int result = getBlockAddress().hashCode();
           result = 31 * result + getTransactionId().hashCode();
           result = 31 * result + getBlockTimestamp().hashCode();
           result = 31 * result + Arrays.hashCode(getBlockHash());
           result = 31 * result + Arrays.hashCode(getEntriesHash());
           result = 31 * result + Arrays.hashCode(getPreviousBlockHash());
           result = 31 * result + Arrays.deepHashCode(getEntriesHashList());
           result = 31 * result + getTransactionInfo().hashCode();
           result = 31 * result + (getRedactionInfo() != null ? getRedactionInfo().hashCode() : 0);
           result = 31 * result + (getRevisions() != null ? getRevisions().hashCode() : 0);
           return result;
       }
   
       /**
        * This method validates that the hashes of the components of a journal block make up the block
        * hash that is provided with the block itself.
        *
        * The components that contribute to the hash of the journal block consist of the following:
        *   - user transaction information (contained in [transactionInfo])
        *   - user redaction information (contained in [redactionInfo])
        *   - user revisions (contained in [revisions])
        *   - hashes of internal-only system metadata (contained in [revisions] and in [entriesHashList])
        *   - the previous block hash
        *
        * If any of the computed hashes of user information cannot be validated or any of the system
        * hashes do not result in the correct computed values, this method will throw an IllegalArgumentException.
        *
        * Internal-only system metadata is represented by its hash, and can be present in the form of certain
        * items in the [revisions] list that only contain a hash and no user data, as well as some hashes
        * in [entriesHashList].
        *
        * To validate that the hashes of the user data are valid components of the [blockHash], this method
        * performs the following steps:
        *
        * 1. Compute the hash of the [transactionInfo] and validate that it is included in the [entriesHashList].
        * 2. Compute the hash of the [redactionInfo], if present, and validate that it is included in the [entriesHashList].
        * 3. Validate the hash of each user revision was correctly computed and matches the hash published
        * with that revision.
        * 4. Compute the hash of the [revisions] by treating the revision hashes as the leaf nodes of a Merkle tree
        * and calculating the root hash of that tree. Then validate that hash is included in the [entriesHashList].
        * 5. Compute the hash of the [entriesHashList] by treating the hashes as the leaf nodes of a Merkle tree
        * and calculating the root hash of that tree. Then validate that hash matches [entriesHash].
        * 6. Finally, compute the block hash by computing the hash resulting from concatenating the [entriesHash]
        * and previous block hash, and validate that the result matches the [blockHash] provided by QLDB with the block.
        *
        * This method is called by ValidateQldbHashChain::verify for each journal block to validate its
        * contents before verifying that the hash chain between consecutive blocks is correct.
        */
       public void verifyBlockHash() {
           Set<ByteBuffer> entriesHashSet = new HashSet<>();
           Arrays.stream(entriesHashList).forEach(hash -> entriesHashSet.add(wrap(hash).asReadOnlyBuffer()));
   
           byte[] computedTransactionInfoHash = computeTransactionInfoHash();
           if (!entriesHashSet.contains(wrap(computedTransactionInfoHash).asReadOnlyBuffer())) {
               throw new IllegalArgumentException(
                       "Block transactionInfo hash is not contained in the QLDB block entries hash list.");
           }
   
           if (redactionInfo != null) {
               byte[] computedRedactionInfoHash = computeRedactionInfoHash();
               if (!entriesHashSet.contains(wrap(computedRedactionInfoHash).asReadOnlyBuffer())) {
                   throw new IllegalArgumentException(
                           "Block redactionInfo hash is not contained in the QLDB block entries hash list.");
               }
           }
   
           if (revisions != null) {
               revisions.forEach(QldbRevision::verifyRevisionHash);
               byte[] computedRevisionsHash = computeRevisionsHash();
               if (!entriesHashSet.contains(wrap(computedRevisionsHash).asReadOnlyBuffer())) {
                   throw new IllegalArgumentException(
                           "Block revisions list hash is not contained in the QLDB block entries hash list.");
               }
           }
   
           byte[] computedEntriesHash = computeEntriesHash();
           if (!Arrays.equals(computedEntriesHash, entriesHash)) {
               throw new IllegalArgumentException("Computed entries hash does not match entries hash provided in the block.");
           }
   
           byte[] computedBlockHash = Verifier.dot(computedEntriesHash, previousBlockHash);
           if (!Arrays.equals(computedBlockHash, blockHash)) {
               throw new IllegalArgumentException("Computed block hash does not match block hash provided in the block.");
           }
       }
   
       private byte[] computeTransactionInfoHash() {
           try {
               return QldbIonUtils.hashIonValue(Constants.MAPPER.writeValueAsIonValue(transactionInfo));
           } catch (IOException e) {
               throw new IllegalArgumentException("Could not compute transactionInfo hash to verify block hash.", e);
           }
       }
   
       private byte[] computeRedactionInfoHash() {
           try {
               return QldbIonUtils.hashIonValue(Constants.MAPPER.writeValueAsIonValue(redactionInfo));
           } catch (IOException e) {
               throw new IllegalArgumentException("Could not compute redactionInfo hash to verify block hash.", e);
           }
       }
   
       private byte[] computeRevisionsHash() {
           return Verifier.calculateMerkleTreeRootHash(revisions.stream().map(QldbRevision::getHash).collect(Collectors.toList()));
       }
   
       private byte[] computeEntriesHash() {
           return Verifier.calculateMerkleTreeRootHash(Arrays.asList(entriesHashList));
       }
   }
   ```

1. 다음 프로그램(`ValidateQldbHashChain.java`)을 컴파일하고 실행하여 다음 단계를 수행합니다.

   1. `vehicle-registration` 원장의 저널 블록을 라는 Amazon S3 버킷으로 내보냅니다**qldb-tutorial-journal-export-*111122223333***( AWS 계정 숫자로 대체).

   1. `verifyBlockHash()`를 호출하여 각 블록 내의 개별 해시 구성 요소를 검증합니다.

   1. 저널 블록 간의 해시 체인을 검증합니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.model.ExportJournalToS3Result;
   import com.amazonaws.services.qldb.model.S3EncryptionConfiguration;
   import com.amazonaws.services.qldb.model.S3ObjectEncryptionType;
   import com.amazonaws.services.s3.AmazonS3ClientBuilder;
   
   import java.time.Instant;
   import java.util.Arrays;
   import java.util.List;
   
   import com.amazonaws.services.securitytoken.AWSSecurityTokenServiceClientBuilder;
   import com.amazonaws.services.securitytoken.model.GetCallerIdentityRequest;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.tutorial.qldb.JournalBlock;
   
   /**
    * Validate the hash chain of a QLDB ledger by stepping through its S3 export.
    *
    * This code accepts an exportId as an argument, if exportId is passed the code
    * will use that or request QLDB to generate a new export to perform QLDB hash
    * chain validation.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class ValidateQldbHashChain {
       public static final Logger log = LoggerFactory.getLogger(ValidateQldbHashChain.class);
       private static final int TIME_SKEW = 20;
   
       private ValidateQldbHashChain() { }
   
       /**
        * Export journal contents to a S3 bucket.
        *
        * @return the ExportId of the journal export.
        * @throws InterruptedException if the thread is interrupted while waiting for export to complete.
        */
       private static String createExport() throws InterruptedException {
           String accountId = AWSSecurityTokenServiceClientBuilder.defaultClient()
               .getCallerIdentity(new GetCallerIdentityRequest()).getAccount();
           String bucketName = Constants.JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX + "-" + accountId;
           String prefix = Constants.LEDGER_NAME + "-" + Instant.now().getEpochSecond() + "/";
   
           S3EncryptionConfiguration encryptionConfiguration = new S3EncryptionConfiguration()
                   .withObjectEncryptionType(S3ObjectEncryptionType.SSE_S3);
           ExportJournalToS3Result exportJournalToS3Result = 
               ExportJournal.createJournalExportAndAwaitCompletion(Constants.LEDGER_NAME, 
                       bucketName, prefix, null, encryptionConfiguration, ExportJournal.DEFAULT_EXPORT_TIMEOUT_MS);
   
           return exportJournalToS3Result.getExportId();
       }
   
       /**
        * Validates that the chain hash on the {@link JournalBlock} is valid.
        *
        * @param journalBlocks
        *              {@link JournalBlock} containing hashes to validate.
        * @throws IllegalStateException if previous block hash does not match.
        */
       public static void verify(final List<JournalBlock> journalBlocks) {
           if (journalBlocks.size() == 0) {
               return;
           }
   
           journalBlocks.stream().reduce(null, (previousJournalBlock, journalBlock) -> {
               journalBlock.verifyBlockHash();
               if (previousJournalBlock == null) { return journalBlock; }
               if (!Arrays.equals(previousJournalBlock.getBlockHash(), journalBlock.getPreviousBlockHash())) {
                   throw new IllegalStateException("Previous block hash doesn't match.");
               }
               byte[] blockHash = Verifier.dot(journalBlock.getEntriesHash(), previousJournalBlock.getBlockHash());
               if (!Arrays.equals(blockHash, journalBlock.getBlockHash())) {
                   throw new IllegalStateException("Block hash doesn't match entriesHash dot previousBlockHash, the chain is "
                           + "broken.");
               }
               return journalBlock;
           });
       }
   
       public static void main(final String... args) throws InterruptedException {
           try {
               String exportId;
               if (args.length == 1) {
                   exportId = args[0];
                   log.info("Validating QLDB hash chain for exportId: " + exportId);
               } else {
                   log.info("Requesting QLDB to create an export.");
                   exportId = createExport();
               }
               List<JournalBlock> journalBlocks =
                   JournalS3ExportReader.readExport(DescribeJournalExport.describeExport(Constants.LEDGER_NAME,
                       exportId), AmazonS3ClientBuilder.defaultClient());
               verify(journalBlocks);
           } catch (Exception e) {
               log.error("Unable to perform hash chain verification.", e);
               throw e;
           }
       }
   
   }
   ```

`vehicle-registration` 원장을 더 이상 사용할 필요가 없는 경우 [9단계(선택 사항): 리소스 정리](getting-started.java.step-9.md)로 진행하세요.

# 9단계(선택 사항): 리소스 정리
<a name="getting-started.java.step-9"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

`vehicle-registration` 원장을 계속 사용할 수 있습니다. 그러나 더 이상 필요하지 않은 경우 삭제해야 합니다.

**원장을 삭제하려면**

1. 다음 프로그램(`DeleteLedger.java`)을 컴파일하고 실행하여 `vehicle-registration` 원장 및 모든 콘텐츠를 삭제합니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.DeleteLedgerRequest;
   import com.amazonaws.services.qldb.model.DeleteLedgerResult;
   import com.amazonaws.services.qldb.model.ResourceNotFoundException;
   import com.amazonaws.services.qldb.model.UpdateLedgerRequest;
   import com.amazonaws.services.qldb.model.UpdateLedgerResult;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Delete a ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class DeleteLedger {
       public static final Logger log = LoggerFactory.getLogger(DeleteLedger.class);
       public static final Long LEDGER_DELETION_POLL_PERIOD_MS = 20_000L;
       public static AmazonQLDB client = CreateLedger.getClient();
   
       private DeleteLedger() { }
   
       public static void main(String... args) throws Exception {
           try {
               setDeletionProtection(Constants.LEDGER_NAME, false);
   
               delete(Constants.LEDGER_NAME);
   
               waitForDeleted(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to delete the ledger.", e);
               throw e;
           }
       }
   
       /**
        * Send a request to the QLDB database to delete the specified ledger.
        *
        * @param ledgerName
        *              Name of the ledger to be deleted.
        * @return DeleteLedgerResult.
        */
       public static DeleteLedgerResult delete(final String ledgerName) {
           log.info("Attempting to delete the ledger with name: {}...", ledgerName);
           DeleteLedgerRequest request = new DeleteLedgerRequest().withName(ledgerName);
           DeleteLedgerResult result = client.deleteLedger(request);
           log.info("Success.");
           return result;
       }
   
       /**
        * Wait for the ledger to be deleted.
        *
        * @param ledgerName
        *              Name of the ledger being deleted.
        * @throws InterruptedException if thread is being interrupted.
        */
       public static void waitForDeleted(final String ledgerName) throws InterruptedException {
           log.info("Waiting for the ledger to be deleted...");
           while (true) {
               try {
                   DescribeLedger.describe(ledgerName);
                   log.info("The ledger is still being deleted. Please wait...");
                   Thread.sleep(LEDGER_DELETION_POLL_PERIOD_MS);
               } catch (ResourceNotFoundException ex) {
                   log.info("Success. The ledger is deleted.");
                   break;
               }
           }
       }
       
       public static UpdateLedgerResult setDeletionProtection(String ledgerName, boolean deletionProtection) {
           log.info("Let's set deletionProtection to {} for the ledger with name {}", deletionProtection, ledgerName);
           UpdateLedgerRequest request = new UpdateLedgerRequest()
                   .withName(ledgerName)
                   .withDeletionProtection(deletionProtection);
   
           UpdateLedgerResult result = client.updateLedger(request);
           log.info("Success. Ledger updated: {}", result);
           return result;
       }
   }
   ```
**참고**  
원장에 대해 삭제 방지가 활성화된 경우 QLDB API를 사용하여 원장을 삭제하기 전에 먼저 이를 비활성화해야 합니다.

1. [이전 단계](getting-started.java.step-8.md)에서 저널 데이터를 내보냈는데 더 이상 필요하지 않은 경우, Amazon S3 콘솔을 사용하여 S3 버킷을 삭제하세요.

   [https://console.aws.amazon.com/s3/](https://console.aws.amazon.com/s3/)에서 Amazon S3 콘솔을 엽니다.

# Amazon QLDB Node.js 자습서
<a name="getting-started.nodejs.tutorial"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 자습서 샘플 애플리케이션 구현에서는 Node.js의 AWS SDK for JavaScript와 함께 Amazon QLDB 드라이버를 사용하여 QLDB 원장을 생성하고 샘플 데이터로 채웁니다.

이 자습서로 학습하면서 관리 API 작업에 대해서 [AWS SDK for JavaScript API 참조](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/)를 참조할 수 있습니다. 트랜잭션 데이터 작업의 경우 [Node.js API용 QLDB 드라이버 참조](https://amazon-qldb-docs.s3.amazonaws.com/drivers/nodejs/3.1.0/index.html)를 참조할 수 있습니다.

**참고**  
해당하는 경우 일부 자습서 단계에는 지원되는 Node.js QLDB 드라이버의 각 주요 버전에 대해 서로 다른 명령 또는 코드 예제가 있습니다.

**Topics**
+ [Amazon QLDB Node.js 샘플 애플리케이션 설치](sample-app.nodejs.md)
+ [1단계: 새 원장 생성](getting-started.nodejs.step-1.md)
+ [2단계: 원장과의 연결을 테스트](getting-started.nodejs.step-2.md)
+ [3단계: 테이블, 인덱스 및 샘플 데이터 생성](getting-started.nodejs.step-3.md)
+ [4단계: 원장에서 테이블 쿼리](getting-started.nodejs.step-4.md)
+ [5단계: 원장의 문서 수정](getting-started.nodejs.step-5.md)
+ [6단계: 문서의 개정 기록 보기](getting-started.nodejs.step-6.md)
+ [7단계: 원장에 있는 문서 검증](getting-started.nodejs.step-7.md)
+ [8단계(선택 사항): 리소스 정리](getting-started.nodejs.step-8.md)

# Amazon QLDB Node.js 샘플 애플리케이션 설치
<a name="sample-app.nodejs"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 섹션에서는 단계별 Node.js 자습서를 위해 제공된 Amazon QLDB 샘플 애플리케이션을 설치하고 실행하는 방법을 설명합니다. 이 샘플 애플리케이션의 사용 사례는 차량 등록에 대한 전체 기록 정보를 추적하는 자동차 부서(DMV) 데이터베이스입니다.

Node.js용 DMV 샘플 애플리케이션은 GitHub 리포지토리 [aws-samples/amazon-qldb-dmv-sample-nodejs](https://github.com/aws-samples/amazon-qldb-dmv-sample-nodejs)의 오픈 소스입니다.

## 사전 조건
<a name="sample-app.nodejs.prereqs"></a>

시작하기 전에 Node.js [사전 조건](getting-started.nodejs.md#getting-started.nodejs.prereqs)용 QLDB 드라이버를 완료했는지 확인합니다. 여기에는 Node.js 설치 및 다음 작업이 포함됩니다.

1. 가입합니다 AWS.

1. 적절한 QLDB 권한을 가진 사용자를 생성합니다.

1. 개발을 위한 프로그래밍 방식 액세스 권한을 부여합니다.

이 자습서의 모든 단계를 완료하려면 QLDB API를 통해 원장 리소스에 대한 전체 관리 액세스 권한이 필요합니다.

## 설치
<a name="sample-app.nodejs.install"></a>

**샘플 애플리케이션을 설치하려면**

1. 다음 명령을 입력하여 GitHub에서 샘플 애플리케이션을 복제합니다.

------
#### [ 2.x ]

   ```
   git clone https://github.com/aws-samples/amazon-qldb-dmv-sample-nodejs.git
   ```

------
#### [ 1.x ]

   ```
   git clone -b v1.0.0 https://github.com/aws-samples/amazon-qldb-dmv-sample-nodejs.git
   ```

------

   샘플 애플리케이션은 Node.js 드라이버 및 [Node.js의 JavaScript용AWS SDK](https://aws.amazon.com/sdk-for-node-js)를 포함하여 이 자습서의 전체 소스 코드와 해당 종속성을 패키징합니다. 이 애플리케이션은 TypeScript로 작성되었습니다.

1. `amazon-qldb-dmv-sample-nodejs` 패키지가 복제된 디렉토리로 전환합니다.

   ```
   cd amazon-qldb-dmv-sample-nodejs
   ```

1. 종속성을 클린 설치합니다.

   ```
   npm ci
   ```

1. 패키지를 트랜스파일합니다.

   ```
   npm run build
   ```

   트랜스파일된 JavaScript 파일은 `./dist` 디렉터리에 작성됩니다.

1. [1단계: 새 원장 생성](getting-started.nodejs.step-1.md)로 진행하여 자습서를 시작하고 원장을 생성하세요.

# 1단계: 새 원장 생성
<a name="getting-started.nodejs.step-1"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 단계에서는 `vehicle-registration`라는 이름의 새 Amazon QLDB 원장을 생성합니다

**새 원장을 생성하려면**

1. 이 자습서의 다른 모든 프로그램에서 사용하는 상수 값이 들어 있는 다음 파일(`Constants.ts`)을 검토하세요.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   /**
    * Constant values used throughout this tutorial.
    */
   export const LEDGER_NAME = "vehicle-registration";
   export const LEDGER_NAME_WITH_TAGS = "tags";
   
   export const DRIVERS_LICENSE_TABLE_NAME = "DriversLicense";
   export const PERSON_TABLE_NAME = "Person";
   export const VEHICLE_REGISTRATION_TABLE_NAME = "VehicleRegistration";
   export const VEHICLE_TABLE_NAME = "Vehicle";
   
   export const GOV_ID_INDEX_NAME = "GovId";
   export const LICENSE_NUMBER_INDEX_NAME = "LicenseNumber";
   export const LICENSE_PLATE_NUMBER_INDEX_NAME = "LicensePlateNumber";
   export const PERSON_ID_INDEX_NAME = "PersonId";
   export const VIN_INDEX_NAME = "VIN";
   
   export const RETRY_LIMIT = 4;
   
   export const JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX = "qldb-tutorial-journal-export";
   export const USER_TABLES = "information_schema.user_tables";
   ```

1. 다음 프로그램(`CreateLedger.ts`)을 사용하여 이름이 `vehicle-registration`로 지정된 원장을 생성합니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QLDB } from "aws-sdk";
   import {
       CreateLedgerRequest,
       CreateLedgerResponse,
       DescribeLedgerRequest,
       DescribeLedgerResponse
   } from "aws-sdk/clients/qldb";
   
   import { LEDGER_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   import { sleep } from "./qldb/Util";
   
   const LEDGER_CREATION_POLL_PERIOD_MS = 10000;
   const ACTIVE_STATE = "ACTIVE";
   
   /**
    * Create a new ledger with the specified name.
    * @param ledgerName Name of the ledger to be created.
    * @param qldbClient The QLDB control plane client to use.
    * @returns Promise which fulfills with a CreateLedgerResponse.
    */
   export async function createLedger(ledgerName: string, qldbClient: QLDB): Promise<CreateLedgerResponse> {
       log(`Creating a ledger named: ${ledgerName}...`);
       const request: CreateLedgerRequest = {
           Name: ledgerName,
           PermissionsMode: "ALLOW_ALL"
       }
       const result: CreateLedgerResponse = await qldbClient.createLedger(request).promise();
       log(`Success. Ledger state: ${result.State}.`);
       return result;
   }
   
   /**
    * Wait for the newly created ledger to become active.
    * @param ledgerName Name of the ledger to be checked on.
    * @param qldbClient The QLDB control plane client to use.
    * @returns Promise which fulfills with a DescribeLedgerResponse.
    */
   export async function waitForActive(ledgerName: string, qldbClient: QLDB): Promise<DescribeLedgerResponse> {
       log(`Waiting for ledger ${ledgerName} to become active...`);
       const request: DescribeLedgerRequest = {
           Name: ledgerName
       }
       while (true) {
           const result: DescribeLedgerResponse = await qldbClient.describeLedger(request).promise();
           if (result.State === ACTIVE_STATE) {
               log("Success. Ledger is active and ready to be used.");
               return result;
           }
           log("The ledger is still creating. Please wait...");
           await sleep(LEDGER_CREATION_POLL_PERIOD_MS);
       }
   }
   
   /**
    * Create a ledger and wait for it to be active.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbClient: QLDB = new QLDB();
           await createLedger(LEDGER_NAME, qldbClient);
           await waitForActive(LEDGER_NAME, qldbClient);
       } catch (e) {
           error(`Unable to create the ledger: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
`createLedger` 호출 시 원장 이름과 권한 모드를 지정해야 합니다. 원장 데이터의 보안을 극대화하려면 `STANDARD` 권한 모드를 사용할 것을 권장합니다.
원장을 생성할 때 기본적으로 *삭제 방지*가 활성화됩니다. 이 기능은 사용자가 원장을 삭제하는 것을 방지하는 QLDB의 기능입니다. QLDB API 또는 AWS Command Line Interface ()를 사용하여 원장 생성 시 삭제 방지 기능을 비활성화할 수 있습니다AWS CLI.
선택적으로, 원장에 첨부할 태그를 지정할 수도 있습니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/CreateLedger.js
   ```

새 원장과의 연결을 확인하려면 [2단계: 원장과의 연결을 테스트](getting-started.nodejs.step-2.md)로 이동하세요.

# 2단계: 원장과의 연결을 테스트
<a name="getting-started.nodejs.step-2"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 단계에서는 트랜잭션 데이터 API 엔드포인트를 사용하여 Amazon QLDB의 `vehicle-registration` 원장에 연결할 수 있는지 확인합니다.

**원장과의 연결을 테스트하려면**

1. 다음 프로그램(`ConnectToLedger.ts`)을 사용하여 `vehicle-registration` 원장에 대한 데이터 세션 연결을 생성합니다.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, RetryConfig  } from "amazon-qldb-driver-nodejs";
   import { ClientConfiguration } from "aws-sdk/clients/qldbsession";
   
   import { LEDGER_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   
   const qldbDriver: QldbDriver = createQldbDriver();
   
   /**
    * Create a driver for creating sessions.
    * @param ledgerName The name of the ledger to create the driver on.
    * @param serviceConfigurationOptions The configurations for the AWS SDK client that the driver uses.
    * @returns The driver for creating sessions.
    */
   export function createQldbDriver(
       ledgerName: string = LEDGER_NAME,
       serviceConfigurationOptions: ClientConfiguration = {}
   ): QldbDriver {
       const retryLimit = 4;
       const maxConcurrentTransactions = 10;
       //Use driver's default backoff function (and hence, no second parameter provided to RetryConfig)
       const retryConfig: RetryConfig = new RetryConfig(retryLimit);
       const qldbDriver: QldbDriver = new QldbDriver(ledgerName, serviceConfigurationOptions, maxConcurrentTransactions, retryConfig);
       return qldbDriver;
   }
   
   export function getQldbDriver(): QldbDriver {
       return qldbDriver;
   }
   
   /**
    * Connect to a session for a given ledger using default settings.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           log("Listing table names...");
           const tableNames: string[] = await qldbDriver.getTableNames();
           tableNames.forEach((tableName: string): void => {
               log(tableName);
           });
       } catch (e) {
           error(`Unable to create session: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver  } from "amazon-qldb-driver-nodejs";
   import { ClientConfiguration } from "aws-sdk/clients/qldbsession";
   
   import { LEDGER_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   
   const qldbDriver: QldbDriver = createQldbDriver();
   
   /**
    * Create a driver for creating sessions.
    * @param ledgerName The name of the ledger to create the driver on.
    * @param serviceConfigurationOptions The configurations for the AWS SDK client that the driver uses.
    * @returns The driver for creating sessions.
    */
   export function createQldbDriver(
       ledgerName: string = LEDGER_NAME,
       serviceConfigurationOptions: ClientConfiguration = {}
   ): QldbDriver {
       const qldbDriver: QldbDriver = new QldbDriver(ledgerName, serviceConfigurationOptions);
       return qldbDriver;
   }
   
   export function getQldbDriver(): QldbDriver {
       return qldbDriver;
   }
   
   /**
    * Connect to a session for a given ledger using default settings.
    * @returns Promise which fulfills with void.
    */
   var main = async function(): Promise<void> {
       try {
           log("Listing table names...");
           const tableNames: string[] = await qldbDriver.getTableNames();
           tableNames.forEach((tableName: string): void => {
               log(tableName);
           });
       } catch (e) {
           error(`Unable to create session: ${e}`);
       } 
   }
   
   if (require.main === module) {
       main();
   }
   ```

------
**참고**  
원장에서 데이터 트랜잭션을 실행하려면 지정된 원장에 연결할 QLDB 드라이버 객체를 만들어야 합니다. 이는 [이전 단계](getting-started.nodejs.step-1.md)에서 원장을 생성할 때 사용한 `qldbClient` 객체와는 다른 클라이언트 객체입니다. 이전 클라이언트는 [Amazon QLDB API 참조](api-reference.md)에 나열된 관리 API 작업을 실행하는 데만 사용됩니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/ConnectToLedger.js
   ```

`vehicle-registration` 원장에 테이블을 생성하려면 [3단계: 테이블, 인덱스 및 샘플 데이터 생성](getting-started.nodejs.step-3.md)로 진행하세요.

# 3단계: 테이블, 인덱스 및 샘플 데이터 생성
<a name="getting-started.nodejs.step-3"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB 원장이 활성화되고 연결을 수락하면 차량, 소유자 및 등록 정보에 대한 데이터 테이블 생성을 시작할 수 있습니다. 테이블과 인덱스를 생성한 후 데이터를 로드할 수 있습니다.

이 단계에서는 `vehicle-registration` 원장에 4개의 테이블을 생성합니다.
+ `VehicleRegistration`
+ `Vehicle`
+ `Person`
+ `DriversLicense`

또한 다음과 같은 인덱스를 생성합니다.


****  

| 테이블 이름 | 필드 | 
| --- | --- | 
| VehicleRegistration | VIN | 
| VehicleRegistration | LicensePlateNumber | 
| Vehicle | VIN | 
| Person | GovId | 
| DriversLicense | LicenseNumber | 
| DriversLicense | PersonId | 

샘플 데이터를 삽입할 때는 먼저 `Person` 테이블에 문서를 삽입합니다. 그런 다음 각 `Person` 문서에서 시스템이 할당한 `id`를 사용하여 적절한 `VehicleRegistration` 및 `DriversLicense` 문서의 해당 필드를 채웁니다.

**작은 정보**  
가장 좋은 방법은 문서의 시스템 할당 `id`를 외래 키로 사용하는 것입니다. 고유 식별자(예: 차량의 VIN)로 사용되는 필드를 정의할 수 있지만 문서의 실제  고유 식별자는 `id`입니다. 이 필드는 문서의 메타데이터에 포함되며 *커밋된 뷰*(테이블의 시스텀 정의 뷰)에서 쿼리할 수 있습니다.  
QLDB 뷰에 대한 자세한 내용은 [핵심 개념](ledger-structure.md) 섹션을 참조하세요. 메타데이터에 대해 자세히 알아보려면 [문서 메타데이터 쿼리](working.metadata.md) 섹션을 참조하세요.

**테이블 및 인덱스를 생성하려면**

1. 다음 프로그램(`CreateTable.ts`)을 사용하여 앞서 언급한 테이블을 생성합니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, Result, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import {
       DRIVERS_LICENSE_TABLE_NAME,
       PERSON_TABLE_NAME,
       VEHICLE_REGISTRATION_TABLE_NAME,
       VEHICLE_TABLE_NAME
   } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   
   /**
    * Create multiple tables in a single transaction.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param tableName Name of the table to create.
    * @returns Promise which fulfills with the number of changes to the database.
    */
   export async function createTable(txn: TransactionExecutor, tableName: string): Promise<number> {
       const statement: string = `CREATE TABLE ${tableName}`;
       return await txn.execute(statement).then((result: Result) => {
           log(`Successfully created table ${tableName}.`);
           return result.getResultList().length;
       });
   }
   
   /**
    * Create tables in a QLDB ledger.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbDriver: QldbDriver = getQldbDriver();
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               Promise.all([
                   createTable(txn, VEHICLE_REGISTRATION_TABLE_NAME),
                   createTable(txn, VEHICLE_TABLE_NAME),
                   createTable(txn, PERSON_TABLE_NAME),
                   createTable(txn, DRIVERS_LICENSE_TABLE_NAME)
               ]);
           });
       } catch (e) {
           error(`Unable to create tables: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
이 프로그램은 QLDB 드라이버 인스턴스에서 `executeLambda` 함수를 사용하는 방법을 보여줍니다. 이 예제에서는 단일 Lambda 표현식을 사용하여 여러 `CREATE TABLE` PartiQL 문을 실행합니다.  
이 실행 함수는 암시적으로 트랜잭션을 시작하고 Lambda에서 모든 문을 실행한 다음 트랜잭션을 자동 커밋합니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/CreateTable.js
   ```

1. 앞에서 설명한 대로 다음 프로그램(`CreateIndex.ts`)을 사용하여 테이블에 인덱스를 생성합니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import {
       DRIVERS_LICENSE_TABLE_NAME,
       GOV_ID_INDEX_NAME,
       LICENSE_NUMBER_INDEX_NAME,
       LICENSE_PLATE_NUMBER_INDEX_NAME,
       PERSON_ID_INDEX_NAME,
       PERSON_TABLE_NAME,
       VEHICLE_REGISTRATION_TABLE_NAME,
       VEHICLE_TABLE_NAME,
       VIN_INDEX_NAME
   } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   
   /**
    * Create an index for a particular table.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param tableName Name of the table to add indexes for.
    * @param indexAttribute Index to create on a single attribute.
    * @returns Promise which fulfills with the number of changes to the database.
    */
   export async function createIndex(
       txn: TransactionExecutor, 
       tableName: string, 
       indexAttribute: string
   ): Promise<number> {
       const statement: string = `CREATE INDEX on ${tableName} (${indexAttribute})`;
       return await txn.execute(statement).then((result) => {
           log(`Successfully created index ${indexAttribute} on table ${tableName}.`);
           return result.getResultList().length;
       });
   }
   
   /**
    * Create indexes on tables in a particular ledger.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbDriver: QldbDriver = getQldbDriver();
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               Promise.all([
                   createIndex(txn, PERSON_TABLE_NAME, GOV_ID_INDEX_NAME),
                   createIndex(txn, VEHICLE_TABLE_NAME, VIN_INDEX_NAME),
                   createIndex(txn, VEHICLE_REGISTRATION_TABLE_NAME, VIN_INDEX_NAME),
                   createIndex(txn, VEHICLE_REGISTRATION_TABLE_NAME, LICENSE_PLATE_NUMBER_INDEX_NAME),
                   createIndex(txn, DRIVERS_LICENSE_TABLE_NAME, PERSON_ID_INDEX_NAME),
                   createIndex(txn, DRIVERS_LICENSE_TABLE_NAME, LICENSE_NUMBER_INDEX_NAME)
               ]);
           });
       } catch (e) {
           error(`Unable to create indexes: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/CreateIndex.js
   ```

**데이터를 테이블로 로드하려면**

1. 다음 `.ts` 파일을 검토합니다.

   1. `SampleData.ts` - `vehicle-registration` 테이블에 삽입한 샘플 데이터를 포함합니다.

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      import { Decimal } from "ion-js";
      
      const EMPTY_SECONDARY_OWNERS: object[] = [];
      export const DRIVERS_LICENSE = [
          {
              PersonId: "",
              LicenseNumber: "LEWISR261LL",
              LicenseType: "Learner",
              ValidFromDate: new Date("2016-12-20"),
              ValidToDate: new Date("2020-11-15")
          },
          {
              PersonId: "",
              LicenseNumber : "LOGANB486CG",
              LicenseType: "Probationary",
              ValidFromDate : new Date("2016-04-06"),
              ValidToDate : new Date("2020-11-15")
          },
          {
              PersonId: "",
              LicenseNumber : "744 849 301",
              LicenseType: "Full",
              ValidFromDate : new Date("2017-12-06"),
              ValidToDate : new Date("2022-10-15")
          },
          {
              PersonId: "",
              LicenseNumber : "P626-168-229-765",
              LicenseType: "Learner",
              ValidFromDate : new Date("2017-08-16"),
              ValidToDate : new Date("2021-11-15")
          },
          {
              PersonId: "",
              LicenseNumber : "S152-780-97-415-0",
              LicenseType: "Probationary",
              ValidFromDate : new Date("2015-08-15"),
              ValidToDate : new Date("2021-08-21")
          }
      ];
      export const PERSON = [
          {
              FirstName : "Raul",
              LastName : "Lewis",
              DOB : new Date("1963-08-19"),
              Address : "1719 University Street, Seattle, WA, 98109",
              GovId : "LEWISR261LL",
              GovIdType : "Driver License"
          },
          {
              FirstName : "Brent",
              LastName : "Logan",
              DOB : new Date("1967-07-03"),
              Address : "43 Stockert Hollow Road, Everett, WA, 98203",
              GovId : "LOGANB486CG",
              GovIdType : "Driver License"
          },
          {
              FirstName : "Alexis",
              LastName : "Pena",
              DOB : new Date("1974-02-10"),
              Address : "4058 Melrose Street, Spokane Valley, WA, 99206",
              GovId : "744 849 301",
              GovIdType : "SSN"
          },
          {
              FirstName : "Melvin",
              LastName : "Parker",
              DOB : new Date("1976-05-22"),
              Address : "4362 Ryder Avenue, Seattle, WA, 98101",
              GovId : "P626-168-229-765",
              GovIdType : "Passport"
          },
          {
              FirstName : "Salvatore",
              LastName : "Spencer",
              DOB : new Date("1997-11-15"),
              Address : "4450 Honeysuckle Lane, Seattle, WA, 98101",
              GovId : "S152-780-97-415-0",
              GovIdType : "Passport"
          }
      ];
      export const VEHICLE = [
          {
              VIN : "1N4AL11D75C109151",
              Type : "Sedan",
              Year : 2011,
              Make : "Audi",
              Model : "A5",
              Color : "Silver"
          },
          {
              VIN : "KM8SRDHF6EU074761",
              Type : "Sedan",
              Year : 2015,
              Make : "Tesla",
              Model : "Model S",
              Color : "Blue"
          },
          {
              VIN : "3HGGK5G53FM761765",
              Type : "Motorcycle",
              Year : 2011,
              Make : "Ducati",
              Model : "Monster 1200",
              Color : "Yellow"
          },
          {
              VIN : "1HVBBAANXWH544237",
              Type : "Semi",
              Year : 2009,
              Make : "Ford",
              Model : "F 150",
              Color : "Black"
          },
          {
              VIN : "1C4RJFAG0FC625797",
              Type : "Sedan",
              Year : 2019,
              Make : "Mercedes",
              Model : "CLK 350",
              Color : "White"
          }
      ];
      export const VEHICLE_REGISTRATION = [
          {
              VIN : "1N4AL11D75C109151",
              LicensePlateNumber : "LEWISR261LL",
              State : "WA",
              City : "Seattle",
              ValidFromDate : new Date("2017-08-21"),
              ValidToDate : new Date("2020-05-11"),
              PendingPenaltyTicketAmount : new Decimal(9025, -2),
              Owners : {
                  PrimaryOwner : { PersonId : "" },
                  SecondaryOwners : EMPTY_SECONDARY_OWNERS
              }
          },
          {
              VIN : "KM8SRDHF6EU074761",
              LicensePlateNumber : "CA762X",
              State : "WA",
              City : "Kent",
              PendingPenaltyTicketAmount : new Decimal(13075, -2),
              ValidFromDate : new Date("2017-09-14"),
              ValidToDate : new Date("2020-06-25"),
              Owners : {
                  PrimaryOwner : { PersonId : "" },
                  SecondaryOwners : EMPTY_SECONDARY_OWNERS
              }
          },
          {
              VIN : "3HGGK5G53FM761765",
              LicensePlateNumber : "CD820Z",
              State : "WA",
              City : "Everett",
              PendingPenaltyTicketAmount : new Decimal(44230, -2),
              ValidFromDate : new Date("2011-03-17"),
              ValidToDate : new Date("2021-03-24"),
              Owners : {
                  PrimaryOwner : { PersonId : "" },
                  SecondaryOwners : EMPTY_SECONDARY_OWNERS
              }
          },
          {
              VIN : "1HVBBAANXWH544237",
              LicensePlateNumber : "LS477D",
              State : "WA",
              City : "Tacoma",
              PendingPenaltyTicketAmount : new Decimal(4220, -2),
              ValidFromDate : new Date("2011-10-26"),
              ValidToDate : new Date("2023-09-25"),
              Owners : {
                  PrimaryOwner : { PersonId : "" },
                  SecondaryOwners : EMPTY_SECONDARY_OWNERS
              }
          },
          {
              VIN : "1C4RJFAG0FC625797",
              LicensePlateNumber : "TH393F",
              State : "WA",
              City : "Olympia",
              PendingPenaltyTicketAmount : new Decimal(3045, -2),
              ValidFromDate : new Date("2013-09-02"),
              ValidToDate : new Date("2024-03-19"),
              Owners : {
                  PrimaryOwner : { PersonId : "" },
                  SecondaryOwners : EMPTY_SECONDARY_OWNERS
              }
          }
      ];
      ```

   1. `Util.ts` - [Amazon Ion](ion.md) 데이터를 변환, 구문 분석 및 인쇄하는 도우미 기능을 제공하기 위해 `ion-js` 패키지에서 가져오는 유틸리티 모듈입니다.

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      import { Result, TransactionExecutor } from "amazon-qldb-driver-nodejs";
      import { GetBlockResponse, GetDigestResponse, ValueHolder } from "aws-sdk/clients/qldb";
      import { 
          Decimal, 
          decodeUtf8,
          dom,
          IonTypes, 
          makePrettyWriter, 
          makeReader, 
          Reader, 
          Timestamp, 
          toBase64, 
          Writer
      } from "ion-js";
      
      import { error } from "./LogUtil";
      
      
      
      /**
       * TODO: Replace this with json.stringify
       * Returns the string representation of a given BlockResponse.
       * @param blockResponse The BlockResponse to convert to string.
       * @returns The string representation of the supplied BlockResponse.
       */
      export function blockResponseToString(blockResponse: GetBlockResponse): string {
          let stringBuilder: string = "";
          if (blockResponse.Block.IonText) {
              stringBuilder = stringBuilder + "Block: " + blockResponse.Block.IonText + ", ";
          }
          if (blockResponse.Proof.IonText) {
              stringBuilder = stringBuilder + "Proof: " + blockResponse.Proof.IonText;
          }
          stringBuilder = "{" + stringBuilder + "}";
          const writer: Writer = makePrettyWriter();
          const reader: Reader = makeReader(stringBuilder);
          writer.writeValues(reader);
          return decodeUtf8(writer.getBytes());
      }
      
      /**
       * TODO: Replace this with json.stringify
       * Returns the string representation of a given GetDigestResponse.
       * @param digestResponse The GetDigestResponse to convert to string.
       * @returns The string representation of the supplied GetDigestResponse.
       */
      export function digestResponseToString(digestResponse: GetDigestResponse): string {
          let stringBuilder: string = "";
          if (digestResponse.Digest) {
              stringBuilder += "Digest: " + JSON.stringify(toBase64(<Uint8Array> digestResponse.Digest)) + ", ";
          }
          if (digestResponse.DigestTipAddress.IonText) {
              stringBuilder += "DigestTipAddress: " + digestResponse.DigestTipAddress.IonText;
          }
          stringBuilder = "{" + stringBuilder + "}";
          const writer: Writer = makePrettyWriter();
          const reader: Reader = makeReader(stringBuilder);
          writer.writeValues(reader);
          return decodeUtf8(writer.getBytes());
      }
      
      /**
       * Get the document IDs from the given table.
       * @param txn The {@linkcode TransactionExecutor} for lambda execute.
       * @param tableName The table name to query.
       * @param field A field to query.
       * @param value The key of the given field.
       * @returns Promise which fulfills with the document ID as a string.
       */
      export async function getDocumentId(
          txn: TransactionExecutor,
          tableName: string,
          field: string,
          value: string
      ): Promise<string> {
          const query: string = `SELECT id FROM ${tableName} AS t BY id WHERE t.${field} = ?`;
          let documentId: string = undefined;
          await txn.execute(query, value).then((result: Result) => {
              const resultList: dom.Value[] = result.getResultList();
              if (resultList.length === 0) {
                  throw new Error(`Unable to retrieve document ID using ${value}.`);
              }
              documentId = resultList[0].get("id").stringValue();
      
          }).catch((err: any) => {
              error(`Error getting documentId: ${err}`);
          });
          return documentId;
      }
      
      /**
       * Sleep for the specified amount of time.
       * @param ms The amount of time to sleep in milliseconds.
       * @returns Promise which fulfills with void.
       */
      export function sleep(ms: number): Promise<void> {
          return new Promise(resolve => setTimeout(resolve, ms));
      }
      
      /**
       * Find the value of a given path in an Ion value. The path should contain a blob value.
       * @param value The Ion value that contains the journal block attributes.
       * @param path The path to a certain attribute.
       * @returns Uint8Array value of the blob, or null if the attribute cannot be found in the Ion value
       *                  or is not of type Blob
       */
      export function getBlobValue(value: dom.Value, path: string): Uint8Array | null {
          const attribute: dom.Value = value.get(path);
          if (attribute !== null && attribute.getType() === IonTypes.BLOB) {
              return attribute.uInt8ArrayValue();
          }
          return null;
      }
      
      /**
       * TODO: Replace this with json.stringify
       * Returns the string representation of a given ValueHolder.
       * @param valueHolder The ValueHolder to convert to string.
       * @returns The string representation of the supplied ValueHolder.
       */
      export function valueHolderToString(valueHolder: ValueHolder): string {
          const stringBuilder: string = `{ IonText: ${valueHolder.IonText}}`;
          const writer: Writer = makePrettyWriter();
          const reader: Reader = makeReader(stringBuilder);
          writer.writeValues(reader);
          return decodeUtf8(writer.getBytes());
      }
      
      /**
       * Converts a given value to Ion using the provided writer.
       * @param value The value to convert to Ion.
       * @param ionWriter The Writer to pass the value into.
       * @throws Error: If the given value cannot be converted to Ion.
       */
      export function writeValueAsIon(value: any, ionWriter: Writer): void {
          switch (typeof value) {
              case "string":
                  ionWriter.writeString(value);
                  break;
              case "boolean":
                  ionWriter.writeBoolean(value);
                  break;
              case "number":
                      ionWriter.writeInt(value);
                      break;
              case "object":
                  if (Array.isArray(value)) {
                      // Object is an array.
                      ionWriter.stepIn(IonTypes.LIST);
      
                      for (const element of value) {
                          writeValueAsIon(element, ionWriter);
                      }
      
                      ionWriter.stepOut();
                  } else if (value instanceof Date) {
                      // Object is a Date.
                      ionWriter.writeTimestamp(Timestamp.parse(value.toISOString()));
                  } else if (value instanceof Decimal) {
                      // Object is a Decimal.
                      ionWriter.writeDecimal(value);
                  } else if (value === null) {
                      ionWriter.writeNull(IonTypes.NULL);
                  } else {
                      // Object is a struct.
                      ionWriter.stepIn(IonTypes.STRUCT);
      
                      for (const key of Object.keys(value)) {
                          ionWriter.writeFieldName(key);
                          writeValueAsIon(value[key], ionWriter);
                      }
                      ionWriter.stepOut();
                  }
                  break;
              default:
                  throw new Error(`Cannot convert to Ion for type: ${(typeof value)}.`);
          }
      }
      ```
**참고**  
이 `getDocumentId` 함수는 테이블에서 시스템 할당 문서 ID를 반환하는 쿼리를 실행합니다. 자세한 내용은 [BY 절을 사용하여 문서 ID 쿼리하기](working.metadata.by-clause.md) 섹션을 참조하세요.

1. 다음 프로그램(`InsertDocument.ts`)을 사용하여 샘플 데이터를 테이블에 삽입합니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, Result, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   import { dom } from "ion-js";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import { DRIVERS_LICENSE, PERSON, VEHICLE, VEHICLE_REGISTRATION } from "./model/SampleData";
   import {
       DRIVERS_LICENSE_TABLE_NAME,
       PERSON_TABLE_NAME,
       VEHICLE_REGISTRATION_TABLE_NAME,
       VEHICLE_TABLE_NAME
   } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   
   /**
    * Insert the given list of documents into a table in a single transaction.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param tableName Name of the table to insert documents into.
    * @param documents List of documents to insert.
    * @returns Promise which fulfills with a {@linkcode Result} object.
    */
   export async function insertDocument(
       txn: TransactionExecutor,
       tableName: string,
       documents: object[]
   ): Promise<Result> {
       const statement: string = `INSERT INTO ${tableName} ?`;
       const result: Result = await txn.execute(statement, documents);
       return result;
   }
   
   /**
    * Handle the insertion of documents and updating PersonIds all in a single transaction.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @returns Promise which fulfills with void.
    */
   async function updateAndInsertDocuments(txn: TransactionExecutor): Promise<void> {
       log("Inserting multiple documents into the 'Person' table...");
       const documentIds: Result = await insertDocument(txn, PERSON_TABLE_NAME, PERSON);
   
       const listOfDocumentIds: dom.Value[] = documentIds.getResultList();
       log("Updating PersonIds for 'DriversLicense' and PrimaryOwner for 'VehicleRegistration'...");
       updatePersonId(listOfDocumentIds);
   
       log("Inserting multiple documents into the remaining tables...");
       await Promise.all([
           insertDocument(txn, DRIVERS_LICENSE_TABLE_NAME, DRIVERS_LICENSE),
           insertDocument(txn, VEHICLE_REGISTRATION_TABLE_NAME, VEHICLE_REGISTRATION),
           insertDocument(txn, VEHICLE_TABLE_NAME, VEHICLE)
       ]);
   }
   
   /**
    * Update the PersonId value for DriversLicense records and the PrimaryOwner value for VehicleRegistration records.
    * @param documentIds List of document IDs.
    */
   export function updatePersonId(documentIds: dom.Value[]): void {
       documentIds.forEach((value: dom.Value, i: number) => {
           const documentId: string = value.get("documentId").stringValue();
           DRIVERS_LICENSE[i].PersonId = documentId;
           VEHICLE_REGISTRATION[i].Owners.PrimaryOwner.PersonId = documentId;
       });
   }
   
   /**
    * Insert documents into a table in a QLDB ledger.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbDriver: QldbDriver = getQldbDriver();
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               await updateAndInsertDocuments(txn);
           });
       } catch (e) {
           error(`Unable to insert documents: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
이 프로그램은 파라미터화된 값을 사용하여 `execute` 함수를 호출하는 방법을 보여줍니다. 실행하려는 PartiQL 문 외에도 데이터 파라미터를 전달할 수 있습니다. 명령문 문자열에서 물음표(`?`)를 변수 자리 표시자로 사용하세요.
`INSERT` 문이 성공하면 삽입된 각 문서의 `id`이 반환됩니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/InsertDocument.js
   ```

다음으로 `SELECT` 문을 사용하여 `vehicle-registration` 원장의 테이블에서 데이터를 읽을 수 있습니다. [4단계: 원장에서 테이블 쿼리](getting-started.nodejs.step-4.md)로 이동합니다.

# 4단계: 원장에서 테이블 쿼리
<a name="getting-started.nodejs.step-4"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB 원장에 테이블을 생성하고 데이터를 로드한 후 쿼리를 실행하여 방금 삽입한 차량 등록 데이터를 검토할 수 있습니다. QLDB는 [PartiQL](ql-reference.md)을 쿼리 언어로 사용하고 [Amazon Ion](ion.md)을 문서 지향 데이터 모델로 사용합니다.

PartiQL은 Ion과 함께 작동하도록 확장된 오픈 소스 SQL 호환 쿼리 언어입니다. PartiQL을 사용하면 익숙한 SQL 연산자를 사용하여 데이터를 삽입, 쿼리 및 관리할 수 있습니다. Amazon Ion은 JSON의 상위 집합입니다. Ion은 정형, 반정형 및 중첩 데이터를 저장하고 처리할 수 있는 유연성을 제공하는 오픈 소스 문서 기반 데이터 형식입니다.

이 단계에서는 `SELECT` 명령문을 사용하여 `vehicle-registration` 원장의 테이블에서 데이터를 읽습니다.

**주의**  
인덱싱된 조회 없이 QLDB에서 쿼리를 실행하면 전체 테이블 스캔이 호출됩니다. PartiQL은 SQL과 호환되므로 이러한 쿼리를 지원합니다. 하지만 QLDB의 프로덕션 사용 사례에 대해서는 테이블 스캔을 실행하지 *마세요.*. 테이블 스캔은 동시성 충돌 및 트랜잭션 시간 초과를 포함하여 대규모 테이블에서 성능 문제를 일으킬 수 있습니다.  
인덱싱된 필드 또는 문서 ID(예: `WHERE indexedField = 123` 또는 `WHERE indexedField IN (456, 789)`)에서 동등 *연산자*를 사용하여 `WHERE` 조건자 절이 포함된 문을 실행하는 것이 좋습니다. 자세한 내용은 [쿼리 성능 최적화](working.optimize.md)을 참조하세요.

**테이블을 쿼리하려면**

1. 다음 프로그램(`FindVehicles.ts`)을 사용하여 원장에 있는 사람의 이름으로 등록된 모든 차량을 쿼리하세요.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, Result, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   import { dom } from "ion-js";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import { PERSON } from "./model/SampleData";
   import { PERSON_TABLE_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   import { getDocumentId } from "./qldb/Util";
   import { prettyPrintResultList } from "./ScanTable";
   
   /**
    * Query 'Vehicle' and 'VehicleRegistration' tables using a unique document ID in one transaction.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param govId The owner's government ID.
    * @returns Promise which fulfills with void.
    */
   async function findVehiclesForOwner(txn: TransactionExecutor, govId: string): Promise<void> {
       const documentId: string = await getDocumentId(txn, PERSON_TABLE_NAME, "GovId", govId);
       const query: string = "SELECT Vehicle FROM Vehicle INNER JOIN VehicleRegistration AS r " +
                           "ON Vehicle.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?";
   
       await txn.execute(query, documentId).then((result: Result) => {
           const resultList: dom.Value[] = result.getResultList();
           log(`List of vehicles for owner with GovId: ${govId}`);
           prettyPrintResultList(resultList);
       });
   }
   
   /**
    * Find all vehicles registered under a person.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbDriver: QldbDriver = getQldbDriver();
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               await findVehiclesForOwner(txn, PERSON[0].GovId);
           });
       } catch (e) {
           error(`Error getting vehicles for owner: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
먼저 이 프로그램은 이 문서에 대한 `Person` 테이블을 `GovId LEWISR261LL`로 쿼리하여 `id` 메타데이터 필드를 가져옵니다.  
그런 다음 이 문서 `id`를 외래 키로 사용하여 `VehicleRegistration` 테이블을 `PrimaryOwner.PersonId`로 쿼리합니다. 또한 `VIN` 필드의 `Vehicle` 테이블과 `VehicleRegistration`를 조인합니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/FindVehicles.js
   ```

`vehicle-registration` 원장의 테이블에 있는 문서를 수정하는 방법에 대한 자세한 내용은 [5단계: 원장의 문서 수정](getting-started.nodejs.step-5.md)을 참조하세요.

# 5단계: 원장의 문서 수정
<a name="getting-started.nodejs.step-5"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이제 작업할 데이터가 있으므로 Amazon QLDB에서 `vehicle-registration` 원장에 있는 문서를 변경할 수 있습니다. 이 단계에서 다음 코드 예제는 DML(데이터 조작 언어) 문을 실행하는 방법을 보여줍니다. 이러한 명령문은 한 차량의 주 소유자를 업데이트하고 다른 차량에 보조 소유자를 추가합니다.

**문서를 수정하려면**

1. 다음 프로그램(`TransferVehicleOwnership.ts`)을 사용하여 차량의 주 소유자를 원장에 VIN `1N4AL11D75C109151`으로 업데이트하세요.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, Result, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   import { dom } from "ion-js";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import { PERSON, VEHICLE } from "./model/SampleData";
   import { PERSON_TABLE_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   import { getDocumentId } from "./qldb/Util";
   
   /**
    * Query a driver's information using the given ID.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param documentId The unique ID of a document in the Person table.
    * @returns Promise which fulfills with an Ion value containing the person.
    */
   export async function findPersonFromDocumentId(txn: TransactionExecutor, documentId: string): Promise<dom.Value> {
       const query: string = "SELECT p.* FROM Person AS p BY pid WHERE pid = ?";
   
       let personId: dom.Value;
       await txn.execute(query, documentId).then((result: Result) => {
           const resultList: dom.Value[] = result.getResultList();
           if (resultList.length === 0) {
               throw new Error(`Unable to find person with ID: ${documentId}.`);
           }
           personId = resultList[0];
       });
       return personId;
   }
   
   /**
    * Find the primary owner for the given VIN.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param vin The VIN to find primary owner for.
    * @returns Promise which fulfills with an Ion value containing the primary owner.
    */
   export async function findPrimaryOwnerForVehicle(txn: TransactionExecutor, vin: string): Promise<dom.Value> {
       log(`Finding primary owner for vehicle with VIN: ${vin}`);
       const query: string = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?";
   
       let documentId: string = undefined;
       await txn.execute(query, vin).then((result: Result) => {
           const resultList: dom.Value[] = result.getResultList();
           if (resultList.length === 0) {
               throw new Error(`Unable to retrieve document ID using ${vin}.`);
           }
           const PersonIdValue: dom.Value = resultList[0].get("PersonId");
           if (PersonIdValue === null) {
               throw new Error(`Expected field name PersonId not found.`);
           }
           documentId = PersonIdValue.stringValue();
       });
       return findPersonFromDocumentId(txn, documentId);
   }
   
   /**
    * Update the primary owner for a vehicle using the given VIN.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param vin The VIN for the vehicle to operate on.
    * @param documentId New PersonId for the primary owner.
    * @returns Promise which fulfills with void.
    */
   async function updateVehicleRegistration(txn: TransactionExecutor, vin: string, documentId: string): Promise<void> {
       const statement: string = "UPDATE VehicleRegistration AS r SET r.Owners.PrimaryOwner.PersonId = ? WHERE r.VIN = ?";
   
       log(`Updating the primary owner for vehicle with VIN: ${vin}...`);
       await txn.execute(statement, documentId, vin).then((result: Result) => {
           const resultList: dom.Value[] = result.getResultList();
           if (resultList.length === 0) {
               throw new Error("Unable to transfer vehicle, could not find registration.");
           }
           log(`Successfully transferred vehicle with VIN ${vin} to new owner.`);
       });
   }
   
   /**
    * Validate the current owner of the given vehicle and transfer its ownership to a new owner in a single transaction.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param vin The VIN of the vehicle to transfer ownership of.
    * @param currentOwner The GovId of the current owner of the vehicle.
    * @param newOwner The GovId of the new owner of the vehicle.
    */
   export async function validateAndUpdateRegistration(
       txn: TransactionExecutor,
       vin: string,
       currentOwner: string,
       newOwner: string
   ): Promise<void> {
       const primaryOwner: dom.Value = await findPrimaryOwnerForVehicle(txn, vin);
       const govIdValue: dom.Value = primaryOwner.get("GovId");
       if (govIdValue !== null && govIdValue.stringValue() !== currentOwner) {
           log("Incorrect primary owner identified for vehicle, unable to transfer.");
       }
       else {
           const documentId: string = await getDocumentId(txn, PERSON_TABLE_NAME, "GovId", newOwner);
           await updateVehicleRegistration(txn, vin, documentId);
           log("Successfully transferred vehicle ownership!");
       }
   }
   
   /**
    * Find primary owner for a particular vehicle's VIN.
    * Transfer to another primary owner for a particular vehicle's VIN.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbDriver: QldbDriver = getQldbDriver();
   
           const vin: string = VEHICLE[0].VIN;
           const previousOwnerGovId: string = PERSON[0].GovId;
           const newPrimaryOwnerGovId: string = PERSON[1].GovId;
   
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               await validateAndUpdateRegistration(txn, vin, previousOwnerGovId,  newPrimaryOwnerGovId);
           });
       } catch (e) {
           error(`Unable to connect and run queries: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/TransferVehicleOwnership.js
   ```

1. 다음 프로그램(`AddSecondaryOwner.ts`)을 사용하여 차량의 보조 소유자를 원장에 VIN `KM8SRDHF6EU074761`으로 추가하세요.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, Result, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   import { dom } from "ion-js";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import { PERSON, VEHICLE_REGISTRATION } from "./model/SampleData";
   import { PERSON_TABLE_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   import { getDocumentId } from "./qldb/Util";
   import { prettyPrintResultList } from "./ScanTable";
   
   /**
    * Add a secondary owner into 'VehicleRegistration' table for a particular VIN.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param vin VIN of the vehicle to query.
    * @param secondaryOwnerId The secondary owner's person ID.
    * @returns Promise which fulfills with void.
    */
   export async function addSecondaryOwner(
       txn: TransactionExecutor, 
       vin: string, 
       secondaryOwnerId: string
   ): Promise<void> {
       log(`Inserting secondary owner for vehicle with VIN: ${vin}`);
       const query: string =
           `FROM VehicleRegistration AS v WHERE v.VIN = ? INSERT INTO v.Owners.SecondaryOwners VALUE ?`;
   
       const personToInsert = {PersonId: secondaryOwnerId};
       await txn.execute(query, vin, personToInsert).then(async (result: Result) => {
           const resultList: dom.Value[] = result.getResultList();
           log("VehicleRegistration Document IDs which had secondary owners added: ");
           prettyPrintResultList(resultList);
       });
   }
   
   /**
    * Query for a document ID with a government ID.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param governmentId The government ID to query with.
    * @returns Promise which fulfills with the document ID as a string.
    */
   export async function getDocumentIdByGovId(txn: TransactionExecutor, governmentId: string): Promise<string> {
       const documentId: string = await getDocumentId(txn, PERSON_TABLE_NAME, "GovId", governmentId);
       return documentId;
   }
   
   /**
    * Check whether a driver has already been registered for the given VIN.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param vin VIN of the vehicle to query.
    * @param secondaryOwnerId The secondary owner's person ID.
    * @returns Promise which fulfills with a boolean.
    */
   export async function isSecondaryOwnerForVehicle(
       txn: TransactionExecutor,
       vin: string,
       secondaryOwnerId: string
   ): Promise<boolean> {
       log(`Finding secondary owners for vehicle with VIN: ${vin}`);
       const query: string = "SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?";
   
       let doesExist: boolean = false;
   
       await txn.execute(query, vin).then((result: Result) => {
           const resultList: dom.Value[] = result.getResultList();
   
           resultList.forEach((value: dom.Value) => {
               const secondaryOwnersList: dom.Value[] = value.get("SecondaryOwners").elements();
   
               secondaryOwnersList.forEach((secondaryOwner) => {
                   const personId: dom.Value = secondaryOwner.get("PersonId");
                   if (personId !== null &&  personId.stringValue() === secondaryOwnerId) {
                       doesExist = true;
                   }
               });
           });
       });
       return doesExist;
   }
   
   /**
    * Finds and adds secondary owners for a vehicle.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbDriver: QldbDriver = getQldbDriver();
           const vin: string = VEHICLE_REGISTRATION[1].VIN;
           const govId: string = PERSON[0].GovId;
   
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               const documentId: string = await getDocumentIdByGovId(txn, govId);
   
               if (await isSecondaryOwnerForVehicle(txn, vin, documentId)) {
                   log(`Person with ID ${documentId} has already been added as a secondary owner of this vehicle.`);
               } else {
                   await addSecondaryOwner(txn, vin, documentId);
               }
           });
   
           log("Secondary owners successfully updated.");
       } catch (e) {
           error(`Unable to add secondary owner: ${e}`);
       } 
   }
   
   if (require.main === module) {
       main();
   }
   ```

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/AddSecondaryOwner.js
   ```

`vehicle-registration` 원장의 이러한 변경 사항을 검토하려면 [6단계: 문서의 개정 기록 보기](getting-started.nodejs.step-6.md)을 참조하세요.

# 6단계: 문서의 개정 기록 보기
<a name="getting-started.nodejs.step-6"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

[이전 단계](getting-started.nodejs.step-5.md)에서 차량의 등록 데이터를 수정한 후, 등록된 모든 소유자 및 기타 업데이트된 필드의 기록을 쿼리할 수 있습니다. 이 단계에서는 `vehicle-registration` 원장의 `VehicleRegistration` 테이블에 있는 문서의 개정 기록을 쿼리합니다.

**개정 기록을 보려면**

1. 다음 프로그램(`QueryHistory.ts`)을 사용하여 VIN `1N4AL11D75C109151`로 `VehicleRegistration` 문서의 개정 기록을 쿼리합니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, Result, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   import { dom } from "ion-js";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import { VEHICLE_REGISTRATION } from "./model/SampleData";
   import { VEHICLE_REGISTRATION_TABLE_NAME } from "./qldb/Constants";
   import { prettyPrintResultList } from "./ScanTable";
   import { error, log } from "./qldb/LogUtil";
   import { getDocumentId } from "./qldb/Util";
   
   /**
    * Find previous primary owners for the given VIN in a single transaction.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param vin The VIN to find previous primary owners for.
    * @returns Promise which fulfills with void.
    */
   async function previousPrimaryOwners(txn: TransactionExecutor, vin: string): Promise<void> {
       const documentId: string = await getDocumentId(txn, VEHICLE_REGISTRATION_TABLE_NAME, "VIN", vin);
       const todaysDate: Date = new Date();
       // set todaysDate back one minute to ensure end time is in the past
       // by the time the request reaches our backend
       todaysDate.setMinutes(todaysDate.getMinutes() - 1);
       const threeMonthsAgo: Date = new Date(todaysDate);
       threeMonthsAgo.setMonth(todaysDate.getMonth() - 3);
   
       const query: string =
           `SELECT data.Owners.PrimaryOwner, metadata.version FROM history ` +
           `(${VEHICLE_REGISTRATION_TABLE_NAME}, \`${threeMonthsAgo.toISOString()}\`, \`${todaysDate.toISOString()}\`) ` +
           `AS h WHERE h.metadata.id = ?`;
   
       await txn.execute(query, documentId).then((result: Result) => {
           log(`Querying the 'VehicleRegistration' table's history using VIN: ${vin}.`);
           const resultList: dom.Value[] = result.getResultList();
           prettyPrintResultList(resultList);
       });
   }
   
   /**
    * Query a table's history for a particular set of documents.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbDriver: QldbDriver = getQldbDriver();
           const vin: string = VEHICLE_REGISTRATION[0].VIN;
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               await previousPrimaryOwners(txn, vin);
           });
       } catch (e) {
           error(`Unable to query history to find previous owners: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
다음 구문에 내장된 [기록 함수](working.history.md#working.history.function)를 쿼리하여 문서의 개정 기록을 볼 수 있습니다  

     ```
     SELECT * FROM history( table_name [, `start-time` [, `end-time` ] ] ) AS h
     [ WHERE h.metadata.id = 'id' ]
     ```
*시작 시간*과 *종료 시간*은 모두 선택 사항입니다. 이 값은 백틱(``...``)으로 표시할 수 있는 Amazon Ion 리터럴 값입니다. 자세한 내용은 [Amazon QLDB에서 PartiQL을 사용한 Ion 쿼리](ql-reference.query.md)을 참조하세요.
가장 좋은 방법은 날짜 범위(*시작 시간* 및 *종료 시간*)와 문서 ID(`metadata.id`)를 모두 사용하여 기록 쿼리를 한정하는 것입니다. QLDB는 트랜잭션에서 `SELECT` 쿼리를 처리하며, 이 쿼리에는 [트랜잭션 시간 초과 제한](limits.md#limits.fixed)이 적용됩니다.  
QLDB 기록은 문서 ID로 인덱싱되며, 이번에는 추가 기록 인덱스를 만들 수 없습니다. 시작 시간과 종료 시간을 포함하는 기록 쿼리는 날짜 범위 한정이라는 이점을 갖습니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/QueryHistory.js
   ```

`vehicle-registration` 원장의 문서 개정을 암호화 방식으로 검증하려면 [7단계: 원장에 있는 문서 검증](getting-started.nodejs.step-7.md)으로 진행하세요.

# 7단계: 원장에 있는 문서 검증
<a name="getting-started.nodejs.step-7"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB를 사용하면 SHA-256 암호화 해싱을 사용하여 원장 저널에 있는 문서의 무결성을 효율적으로 검증할 수 있습니다. QLDB에서 검증 및 암호화 해싱이 작동하는 방식에 대한 자세한 내용은 [Amazon QLDB에서의 데이터 확인](verification.md)을 참조하세요.

이 단계에서는 `vehicle-registration` 원장의 `VehicleRegistration` 테이블에 있는 문서 개정을 검증합니다. 먼저 다이제스트를 요청합니다. 다이제스트는 출력 파일로 반환되며 원장의 전체 변경 내역에 대한 서명 역할을 합니다. 그런 다음 해당 다이제스트와 관련된 개정 증거를 요청합니다. 이 증거를 사용하면 모든 유효성 검사를 통과한 경우 개정 내용의 무결성을 확인할 수 있습니다.

**문서 개정을 검증하려면**

1. 검증에 필요한 QLDB 객체가 들어 있는 다음 `.ts` 파일을 검토하세요.

   1. `BlockAddress.ts`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      import { ValueHolder } from "aws-sdk/clients/qldb";
      import { dom, IonTypes } from "ion-js";
      
      export class BlockAddress {
          _strandId: string;
          _sequenceNo: number;
      
          constructor(strandId: string, sequenceNo: number) {
              this._strandId = strandId;
              this._sequenceNo = sequenceNo;
          }
      }
      
      /**
       * Convert a block address from an Ion value into a ValueHolder.
       * Shape of the ValueHolder must be: {'IonText': "{strandId: <"strandId">, sequenceNo: <sequenceNo>}"}
       * @param value The Ion value that contains the block address values to convert.
       * @returns The ValueHolder that contains the strandId and sequenceNo.
       */
      export function blockAddressToValueHolder(value: dom.Value): ValueHolder {
          const blockAddressValue : dom.Value = getBlockAddressValue(value);
          const strandId: string = getStrandId(blockAddressValue);
          const sequenceNo: number = getSequenceNo(blockAddressValue);
          const valueHolder: string = `{strandId: "${strandId}", sequenceNo: ${sequenceNo}}`;
          const blockAddress: ValueHolder = {IonText: valueHolder};
          return blockAddress;
      }
      
      /**
       * Helper method that to get the Metadata ID.
       * @param value The Ion value.
       * @returns The Metadata ID.
       */
      export function getMetadataId(value: dom.Value): string {
          const metaDataId: dom.Value = value.get("id");
          if (metaDataId === null) {
              throw new Error(`Expected field name id, but not found.`);
          }
          return metaDataId.stringValue();
      }
      
      /**
       * Helper method to get the Sequence No.
       * @param value The Ion value.
       * @returns The Sequence No.
       */
      export function getSequenceNo(value : dom.Value): number {
          const sequenceNo: dom.Value = value.get("sequenceNo");
          if (sequenceNo === null) {
              throw new Error(`Expected field name sequenceNo, but not found.`);
          }
          return sequenceNo.numberValue();
      }
      
      /**
       * Helper method to get the Strand ID.
       * @param value The Ion value.
       * @returns The Strand ID.
       */
      export function getStrandId(value: dom.Value): string {
          const strandId: dom.Value = value.get("strandId");
          if (strandId === null) {
              throw new Error(`Expected field name strandId, but not found.`);
          }
          return strandId.stringValue();
      }
      
      export function getBlockAddressValue(value: dom.Value) : dom.Value {
          const type = value.getType();
          if (type !== IonTypes.STRUCT) {
              throw new Error(`Unexpected format: expected struct, but got IonType: ${type.name}`);
          }
          const blockAddress: dom.Value = value.get("blockAddress");
          if (blockAddress == null) {
              throw new Error(`Expected field name blockAddress, but not found.`);
          }
          return blockAddress;
      }
      ```

   1. `Verifier.ts`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      import { Digest, ValueHolder } from "aws-sdk/clients/qldb";
      import { createHash } from "crypto";
      import { dom, toBase64 } from "ion-js";
      
      import { getBlobValue } from "./Util";
      
      const HASH_LENGTH: number = 32;
      const UPPER_BOUND: number = 8;
      
      /**
       * Build the candidate digest representing the entire ledger from the Proof hashes.
       * @param proof The Proof object.
       * @param leafHash The revision hash to pair with the first hash in the Proof hashes list.
       * @returns The calculated root hash.
       */
      function buildCandidateDigest(proof: ValueHolder, leafHash: Uint8Array): Uint8Array {
          const parsedProof: Uint8Array[] = parseProof(proof);
          const rootHash: Uint8Array = calculateRootHashFromInternalHash(parsedProof, leafHash);
          return rootHash;
      }
      
      /**
       * Combine the internal hashes and the leaf hash until only one root hash remains.
       * @param internalHashes An array of hash values.
       * @param leafHash The revision hash to pair with the first hash in the Proof hashes list.
       * @returns The root hash constructed by combining internal hashes.
       */
      function calculateRootHashFromInternalHash(internalHashes: Uint8Array[], leafHash: Uint8Array): Uint8Array {
          const rootHash: Uint8Array = internalHashes.reduce(joinHashesPairwise, leafHash);
          return rootHash;
      }
      
      /**
       * Compare two hash values by converting each Uint8Array byte, which is unsigned by default,
       * into a signed byte, assuming they are little endian.
       * @param hash1 The hash value to compare.
       * @param hash2 The hash value to compare.
       * @returns Zero if the hash values are equal, otherwise return the difference of the first pair of non-matching bytes.
       */
      function compareHashValues(hash1: Uint8Array, hash2: Uint8Array): number {
          if (hash1.length !== HASH_LENGTH || hash2.length !== HASH_LENGTH) {
              throw new Error("Invalid hash.");
          }
          for (let i = hash1.length-1; i >= 0; i--) {
              const difference: number = (hash1[i]<<24 >>24) - (hash2[i]<<24 >>24);
              if (difference !== 0) {
                  return difference;
              }
          }
          return 0;
      }
      
      /**
       * Helper method that concatenates two Uint8Array.
       * @param arrays List of array to concatenate, in the order provided.
       * @returns The concatenated array.
       */
      function concatenate(...arrays: Uint8Array[]): Uint8Array {
          let totalLength = 0;
          for (const arr of arrays) {
              totalLength += arr.length;
          }
          const result = new Uint8Array(totalLength);
          let offset = 0;
          for (const arr of arrays) {
              result.set(arr, offset);
              offset += arr.length;
          }
          return result;
      }
      
      /**
       * Flip a single random bit in the given hash value.
       * This method is intended to be used for purpose of demonstrating the QLDB verification features only.
       * @param original The hash value to alter.
       * @returns The altered hash with a single random bit changed.
       */
      export function flipRandomBit(original: any): Uint8Array {
          if (original.length === 0) {
              throw new Error("Array cannot be empty!");
          }
          const bytePos: number = Math.floor(Math.random() * original.length);
          const bitShift: number = Math.floor(Math.random() * UPPER_BOUND);
          const alteredHash: Uint8Array = original;
      
          alteredHash[bytePos] = alteredHash[bytePos] ^ (1 << bitShift);
          return alteredHash;
      }
      
      /**
       * Take two hash values, sort them, concatenate them, and generate a new hash value from the concatenated values.
       * @param h1 Byte array containing one of the hashes to compare.
       * @param h2 Byte array containing one of the hashes to compare.
       * @returns The concatenated array of hashes.
       */
      export function joinHashesPairwise(h1: Uint8Array, h2: Uint8Array): Uint8Array {
          if (h1.length === 0) {
              return h2;
          }
          if (h2.length === 0) {
              return h1;
          }
          let concat: Uint8Array;
          if (compareHashValues(h1, h2) < 0) {
              concat = concatenate(h1, h2);
          } else {
              concat = concatenate(h2, h1);
          }
          const hash = createHash('sha256');
          hash.update(concat);
          const newDigest: Uint8Array = hash.digest();
          return newDigest;
      }
      
      /**
       * Parse the Block object returned by QLDB and retrieve block hash.
       * @param valueHolder A structure containing an Ion string value.
       * @returns The block hash.
       */
      export function parseBlock(valueHolder: ValueHolder): Uint8Array {
          const block: dom.Value = dom.load(valueHolder.IonText);
          const blockHash: Uint8Array = getBlobValue(block, "blockHash");
          return blockHash;
      }
      
      /**
       * Parse the Proof object returned by QLDB into an iterator.
       * The Proof object returned by QLDB is a dictionary like the following:
       * {'IonText': '[{{<hash>}},{{<hash>}}]'}
       * @param valueHolder A structure containing an Ion string value.
       * @returns A list of hash values.
       */
      function parseProof(valueHolder: ValueHolder): Uint8Array[] {
          const proofs : dom.Value = dom.load(valueHolder.IonText);
          return proofs.elements().map(proof => proof.uInt8ArrayValue());
      }
      
      /**
       *  Verify document revision against the provided digest.
       * @param documentHash The SHA-256 value representing the document revision to be verified.
       * @param digest The SHA-256 hash value representing the ledger digest.
       * @param proof The Proof object retrieved from GetRevision.getRevision.
       * @returns If the document revision verifies against the ledger digest.
       */
      export function verifyDocument(documentHash: Uint8Array, digest: Digest, proof: ValueHolder): boolean {
          const candidateDigest = buildCandidateDigest(proof, documentHash);
          return (toBase64(<Uint8Array> digest) === toBase64(candidateDigest));
      }
      ```

1. 두 `.ts` 프로그램(`GetDigest.ts` 및 `GetRevision.ts`)을 사용하여 다음 단계를 수행하세요.
   + `vehicle-registration` 원장에 새 다이제스트를 요청하세요.
   + `VehicleRegistration` 테이블에서 VIN `1N4AL11D75C109151`이 포함된 문서의 각 개정에 대한 증거를 요청합니다.
   + 반환된 다이제스트와 증거를 사용하여 다이제스트를 다시 계산하여 개정 내용을 검증합니다.

   `GetDigest.ts` 프로그램에는 다음 코드가 포함되어 있습니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QLDB } from "aws-sdk";
   import { GetDigestRequest, GetDigestResponse } from "aws-sdk/clients/qldb";
   
   import { LEDGER_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   import { digestResponseToString } from "./qldb/Util";
   
   /**
    * Get the digest of a ledger's journal.
    * @param ledgerName Name of the ledger to operate on.
    * @param qldbClient The QLDB control plane client to use.
    * @returns Promise which fulfills with a GetDigestResponse.
    */
   export async function getDigestResult(ledgerName: string, qldbClient: QLDB): Promise<GetDigestResponse> {
       const request: GetDigestRequest = {
           Name: ledgerName
       };
       const result: GetDigestResponse = await qldbClient.getDigest(request).promise();
       return result;
   }
   
   /**
    * This is an example for retrieving the digest of a particular ledger.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbClient: QLDB = new QLDB();
           log(`Retrieving the current digest for ledger: ${LEDGER_NAME}.`);
           const digest: GetDigestResponse = await getDigestResult(LEDGER_NAME, qldbClient);
           log(`Success. Ledger digest: \n${digestResponseToString(digest)}.`);
       } catch (e) {
           error(`Unable to get a ledger digest: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
`getDigest` 함수를 사용하여 원장에 있는 저널의 현재 *팁*을 포함하는 다이제스트를 요청합니다. 저널 팁은 QLDB가 요청을 수신한 시점을 기준으로 가장 최근에 커밋된 블록을 나타냅니다.

   `GetRevision.ts` 프로그램에는 다음 코드가 포함되어 있습니다.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { QldbDriver, TransactionExecutor } from "amazon-qldb-driver-nodejs";
   import { QLDB } from "aws-sdk";
   import { Digest, GetDigestResponse, GetRevisionRequest, GetRevisionResponse, ValueHolder } from "aws-sdk/clients/qldb";
   import { dom, toBase64 } from "ion-js";
   
   import { getQldbDriver } from "./ConnectToLedger";
   import { getDigestResult } from './GetDigest';
   import { VEHICLE_REGISTRATION } from "./model/SampleData"
   import { blockAddressToValueHolder, getMetadataId } from './qldb/BlockAddress';
   import { LEDGER_NAME } from './qldb/Constants';
   import { error, log } from "./qldb/LogUtil";
   import { getBlobValue, valueHolderToString } from "./qldb/Util";
   import { flipRandomBit, verifyDocument } from "./qldb/Verifier";
   
   /**
    * Get the revision data object for a specified document ID and block address.
    * Also returns a proof of the specified revision for verification.
    * @param ledgerName Name of the ledger containing the document to query.
    * @param documentId Unique ID for the document to be verified, contained in the committed view of the document.
    * @param blockAddress The location of the block to request.
    * @param digestTipAddress The latest block location covered by the digest.
    * @param qldbClient The QLDB control plane client to use.
    * @returns Promise which fulfills with a GetRevisionResponse.
    */
   async function getRevision(
       ledgerName: string,
       documentId: string,
       blockAddress: ValueHolder,
       digestTipAddress: ValueHolder,
       qldbClient: QLDB
   ): Promise<GetRevisionResponse> {
       const request: GetRevisionRequest = {
           Name: ledgerName,
           BlockAddress: blockAddress,
           DocumentId: documentId,
           DigestTipAddress: digestTipAddress
       };
       const result: GetRevisionResponse = await qldbClient.getRevision(request).promise();
       return result;
   }
   
   /**
    * Query the table metadata for a particular vehicle for verification.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param vin VIN to query the table metadata of a specific registration with.
    * @returns Promise which fulfills with a list of Ion values that contains the results of the query.
    */
   export async function lookupRegistrationForVin(txn: TransactionExecutor, vin: string): Promise<dom.Value[]> {
       log(`Querying the 'VehicleRegistration' table for VIN: ${vin}...`);
       let resultList: dom.Value[];
       const query: string = "SELECT blockAddress, metadata.id FROM _ql_committed_VehicleRegistration WHERE data.VIN = ?";
   
       await txn.execute(query, vin).then(function(result) {
         resultList = result.getResultList();
       });
       return resultList;
   }
   
   /**
    * Verify each version of the registration for the given VIN.
    * @param txn The {@linkcode TransactionExecutor} for lambda execute.
    * @param ledgerName The ledger to get the digest from.
    * @param vin VIN to query the revision history of a specific registration with.
    * @param qldbClient The QLDB control plane client to use.
    * @returns Promise which fulfills with void.
    * @throws Error: When verification fails.
    */
   export async function verifyRegistration(
       txn: TransactionExecutor, 
       ledgerName: string, 
       vin: string,
       qldbClient: QLDB
   ): Promise<void> {
       log(`Let's verify the registration with VIN = ${vin}, in ledger = ${ledgerName}.`);
       const digest: GetDigestResponse = await getDigestResult(ledgerName, qldbClient);
       const digestBytes: Digest = digest.Digest;
       const digestTipAddress: ValueHolder = digest.DigestTipAddress;
   
       log(
           `Got a ledger digest: digest tip address = \n${valueHolderToString(digestTipAddress)},
           digest = \n${toBase64(<Uint8Array> digestBytes)}.`
       );
       log(`Querying the registration with VIN = ${vin} to verify each version of the registration...`);
       const resultList: dom.Value[] = await lookupRegistrationForVin(txn, vin);
       log("Getting a proof for the document.");
   
       for (const result of resultList) {
           const blockAddress: ValueHolder =  blockAddressToValueHolder(result);
           const documentId: string = getMetadataId(result);
   
           const revisionResponse: GetRevisionResponse = await getRevision(
               ledgerName, 
               documentId, 
               blockAddress, 
               digestTipAddress,
               qldbClient
           );
   
           const revision: dom.Value = dom.load(revisionResponse.Revision.IonText);
           const documentHash: Uint8Array = getBlobValue(revision, "hash");
           const proof: ValueHolder = revisionResponse.Proof;
           log(`Got back a proof: ${valueHolderToString(proof)}.`);
   
           let verified: boolean = verifyDocument(documentHash, digestBytes, proof);
           if (!verified) {
              throw new Error("Document revision is not verified.");
           } else {
               log("Success! The document is verified.");
           }
           const alteredDocumentHash: Uint8Array = flipRandomBit(documentHash);
   
           log(
               `Flipping one bit in the document's hash and assert that the document is NOT verified.
               The altered document hash is: ${toBase64(alteredDocumentHash)}`
           );
           verified = verifyDocument(alteredDocumentHash, digestBytes, proof);
   
           if (verified) {
               throw new Error("Expected altered document hash to not be verified against digest.");
           } else {
               log("Success! As expected flipping a bit in the document hash causes verification to fail.");
           }
           log(`Finished verifying the registration with VIN = ${vin} in ledger = ${ledgerName}.`);
       }
   }
   
   /**
    * Verify the integrity of a document revision in a QLDB ledger.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbClient: QLDB = new QLDB();
           const qldbDriver: QldbDriver = getQldbDriver();
   
           const registration = VEHICLE_REGISTRATION[0];
           const vin: string = registration.VIN;
   
           await qldbDriver.executeLambda(async (txn: TransactionExecutor) => {
               await verifyRegistration(txn, LEDGER_NAME, vin, qldbClient);
           });
       } catch (e) {
           error(`Unable to verify revision: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
`getRevision` 함수가 지정된 문서 개정에 대한 증거를 반환하면 이 프로그램은 클라이언트 측 API를 사용하여 해당 개정본을 확인합니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/GetRevision.js
   ```

`vehicle-registration` 원장을 더 이상 사용할 필요가 없는 경우 [8단계(선택 사항): 리소스 정리](getting-started.nodejs.step-8.md)로 진행하세요.

# 8단계(선택 사항): 리소스 정리
<a name="getting-started.nodejs.step-8"></a>

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

`vehicle-registration` 원장을 계속 사용할 수 있습니다. 그러나 더 이상 필요하지 않은 경우 삭제해야 합니다.

**원장을 삭제하려면**

1. 다음 프로그램(`DeleteLedger.ts`)을 사용하여 `vehicle-registration` 원장과 모든 내용을 삭제하세요.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   import { isResourceNotFoundException } from "amazon-qldb-driver-nodejs";
   import { AWSError, QLDB } from "aws-sdk";
   import { DeleteLedgerRequest, DescribeLedgerRequest } from "aws-sdk/clients/qldb";
   
   import { setDeletionProtection } from "./DeletionProtection";
   import { LEDGER_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   import { sleep } from "./qldb/Util";
   
   const LEDGER_DELETION_POLL_PERIOD_MS = 20000;
   
   /**
    * Send a request to QLDB to delete the specified ledger.
    * @param ledgerName Name of the ledger to be deleted.
    * @param qldbClient The QLDB control plane client to use.
    * @returns Promise which fulfills with void.
    */
   export async function deleteLedger(ledgerName: string, qldbClient: QLDB): Promise<void> {
       log(`Attempting to delete the ledger with name: ${ledgerName}`);
       const request: DeleteLedgerRequest = {
           Name: ledgerName
       };
       await qldbClient.deleteLedger(request).promise();
       log("Success.");
   }
   
   /**
    * Wait for the ledger to be deleted.
    * @param ledgerName Name of the ledger to be deleted.
    * @param qldbClient The QLDB control plane client to use.
    * @returns Promise which fulfills with void.
    */
   export async function waitForDeleted(ledgerName: string, qldbClient: QLDB): Promise<void> {
       log("Waiting for the ledger to be deleted...");
       const request: DescribeLedgerRequest = {
           Name: ledgerName
       };
       let isDeleted: boolean = false;
       while (true) {
           await qldbClient.describeLedger(request).promise().catch((error: AWSError) => {
               if (isResourceNotFoundException(error)) {
                   isDeleted = true;
                   log("Success. Ledger is deleted.");
               }
           });
           if (isDeleted) {
               break;
           }
           log("The ledger is still being deleted. Please wait...");
           await sleep(LEDGER_DELETION_POLL_PERIOD_MS);
       }
   }
   
   /**
    * Delete a ledger.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           const qldbClient: QLDB = new QLDB();
           await setDeletionProtection(LEDGER_NAME, qldbClient, false);
           await deleteLedger(LEDGER_NAME, qldbClient);
           await waitForDeleted(LEDGER_NAME, qldbClient);
       } catch (e) {
           error(`Unable to delete the ledger: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```
**참고**  
원장에 대해 삭제 방지가 활성화된 경우 QLDB API를 사용하여 원장을 삭제하기 전에 먼저 이를 비활성화해야 합니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/DeleteLedger.js
   ```

# Amazon QLDB Python 자습서
<a name="getting-started.python.tutorial"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 자습서 샘플 애플리케이션 구현에서는 Amazon QLDB 드라이버 AWS SDK for Python (Boto3) 를와 함께 사용하여 QLDB 원장을 생성하고 샘플 데이터로 채웁니다.

이 자습서로 학습하면서 *Python용AWS SDK (Boto3) API 참조*에서 [QLDB 하위 수준 클라이언트](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/qldb.html)를 참조하여 관리 API 작업을 수행할 수 있습니다. 트랜잭션 데이터 작업의 경우 [Python용 QLDB 드라이버 API 참조](https://amazon-qldb-driver-python.readthedocs.io/en/stable/)를 참조할 수 있습니다.

**참고**  
해당하는 경우 일부 자습서 단계에는 Python용 QLDB 드라이버의 지원되는 각 메이저 버전마다 서로 다른 명령 또는 코드 예제가 있습니다.

**Topics**
+ [Amazon QLDB Python 샘플 애플리케이션 설치](sample-app.python.md)
+ [1단계: 새 원장 생성](getting-started.python.step-1.md)
+ [2단계: 원장과의 연결을 테스트](getting-started.python.step-2.md)
+ [3단계: 테이블, 인덱스 및 샘플 데이터 생성](getting-started.python.step-3.md)
+ [4단계: 원장에서 테이블 쿼리](getting-started.python.step-4.md)
+ [5단계: 원장의 문서 수정](getting-started.python.step-5.md)
+ [6단계: 문서의 개정 기록 보기](getting-started.python.step-6.md)
+ [7단계: 원장에 있는 문서 검증](getting-started.python.step-7.md)
+ [8단계(선택 사항): 리소스 정리](getting-started.python.step-8.md)

# Amazon QLDB Python 샘플 애플리케이션 설치
<a name="sample-app.python"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 섹션에서는 단계별 Python 자습서를 위해 제공된 Amazon QLDB 샘플 애플리케이션을 설치하고 실행하는 방법을 설명합니다. 이 샘플 애플리케이션의 사용 사례는 차량 등록에 대한 전체 기록 정보를 추적하는 자동차 부서(DMV) 데이터베이스입니다.

Python용 DMV 샘플 애플리케이션은 GitHub 리포지토리 [aws-samples/amazon-qldb-dmv-sample-python](https://github.com/aws-samples/amazon-qldb-dmv-sample-python) 내 오픈 소스입니다.

## 사전 조건
<a name="sample-app.python.prereqs"></a>

시작하기 전에 Python [사전 조건](getting-started.python.md#getting-started.python.prereqs)용 QLDB 드라이버를 완료했는지 확인합니다. 여기에는 Python 설치 및 다음 작업이 포함됩니다.

1. 가입합니다 AWS.

1. 적절한 QLDB 권한을 가진 사용자를 생성합니다.

1. 개발을 위한 프로그래밍 방식 액세스 권한을 부여합니다.

이 자습서의 모든 단계를 완료하려면 QLDB API를 통해 원장 리소스에 대한 전체 관리 액세스 권한이 필요합니다.

## 설치
<a name="sample-app.python.install"></a>

**샘플 애플리케이션을 설치하려면**

1. 다음 `pip` 명령을 입력하여 GitHub에서 샘플 애플리케이션을 복제하고 설치합니다.

------
#### [ 3.x ]

   ```
   pip install git+https://github.com/aws-samples/amazon-qldb-dmv-sample-python.git
   ```

------
#### [ 2.x ]

   ```
   pip install git+https://github.com/aws-samples/amazon-qldb-dmv-sample-python.git@v1.0.0
   ```

------

   샘플 애플리케이션은 이 자습서의 전체 소스 코드와 Python 드라이버 및 [AWS SDK for Python (Boto3)](https://aws.amazon.com/sdk-for-python)을 포함한 해당 종속성을 패키징합니다.

1. 명령줄에서 코드를 실행하기 전에 현재 작업 디렉터리를 `pyqldbsamples` 패키지가 설치된 위치로 전환하세요. 다음 명령을 입력합니다.

   ```
   cd $(python -c "import pyqldbsamples; print(pyqldbsamples.__path__[0])")
   ```

1. [1단계: 새 원장 생성](getting-started.python.step-1.md)로 진행하여 자습서를 시작하고 원장을 생성하세요.

# 1단계: 새 원장 생성
<a name="getting-started.python.step-1"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 단계에서는 `vehicle-registration`라는 이름의 새 Amazon QLDB 원장을 생성합니다

**새 원장을 생성하려면**

1. 이 자습서의 다른 모든 프로그램에서 사용하는 상수 값이 들어 있는 다음 파일(`constants.py`)을 검토하세요.

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   
   
   class Constants:
       """
       Constant values used throughout this tutorial.
       """
       LEDGER_NAME = "vehicle-registration"
   
       VEHICLE_REGISTRATION_TABLE_NAME = "VehicleRegistration"
       VEHICLE_TABLE_NAME = "Vehicle"
       PERSON_TABLE_NAME = "Person"
       DRIVERS_LICENSE_TABLE_NAME = "DriversLicense"
   
       LICENSE_NUMBER_INDEX_NAME = "LicenseNumber"
       GOV_ID_INDEX_NAME = "GovId"
       VEHICLE_VIN_INDEX_NAME = "VIN"
       LICENSE_PLATE_NUMBER_INDEX_NAME = "LicensePlateNumber"
       PERSON_ID_INDEX_NAME = "PersonId"
   
       JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX = "qldb-tutorial-journal-export"
       USER_TABLES = "information_schema.user_tables"
       S3_BUCKET_ARN_TEMPLATE = "arn:aws:s3:::"
       LEDGER_NAME_WITH_TAGS = "tags"
   
       RETRY_LIMIT = 4
   ```

1. 다음 프로그램(`create_ledger.py`)을 사용하여 이름이 `vehicle-registration`로 지정된 원장을 생성합니다.

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   from time import sleep
   
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   LEDGER_CREATION_POLL_PERIOD_SEC = 10
   ACTIVE_STATE = "ACTIVE"
   
   
   def create_ledger(name):
       """
       Create a new ledger with the specified name.
   
       :type name: str
       :param name: Name for the ledger to be created.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info("Let's create the ledger named: {}...".format(name))
       result = qldb_client.create_ledger(Name=name, PermissionsMode='ALLOW_ALL')
       logger.info('Success. Ledger state: {}.'.format(result.get('State')))
       return result
   
   
   def wait_for_active(name):
       """
       Wait for the newly created ledger to become active.
   
       :type name: str
       :param name: The ledger to check on.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info('Waiting for ledger to become active...')
       while True:
           result = qldb_client.describe_ledger(Name=name)
           if result.get('State') == ACTIVE_STATE:
               logger.info('Success. Ledger is active and ready to use.')
               return result
           logger.info('The ledger is still creating. Please wait...')
           sleep(LEDGER_CREATION_POLL_PERIOD_SEC)
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Create a ledger and wait for it to be active.
       """
       try:
           create_ledger(ledger_name)
           wait_for_active(ledger_name)
       except Exception as e:
           logger.exception('Unable to create the ledger!')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```
**참고**  
`create_ledger` 호출 시 원장 이름과 권한 모드를 지정해야 합니다. 원장 데이터의 보안을 극대화하려면 `STANDARD` 권한 모드를 사용할 것을 권장합니다.
원장을 생성할 때 기본적으로 *삭제 방지*가 활성화됩니다. 이 기능은 사용자가 원장을 삭제하는 것을 방지하는 QLDB의 기능입니다. QLDB API 또는 AWS Command Line Interface ()를 사용하여 원장 생성 시 삭제 방지 기능을 비활성화할 수 있습니다AWS CLI.
선택적으로, 원장에 첨부할 태그를 지정할 수도 있습니다.

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python create_ledger.py
   ```

새 원장과의 연결을 확인하려면 [2단계: 원장과의 연결을 테스트](getting-started.python.step-2.md)로 이동하세요.

# 2단계: 원장과의 연결을 테스트
<a name="getting-started.python.step-2"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 단계에서는 트랜잭션 데이터 API 엔드포인트를 사용하여 Amazon QLDB의 `vehicle-registration` 원장에 연결할 수 있는지 확인합니다.

**원장과의 연결을 테스트하려면**

1. 다음 프로그램(`connect_to_ledger.py`)을 사용하여 `vehicle-registration` 원장에 대한 데이터 세션 연결을 생성합니다.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from botocore.exceptions import ClientError
   
   from pyqldb.driver.qldb_driver import QldbDriver
   from pyqldbsamples.constants import Constants
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def create_qldb_driver(ledger_name=Constants.LEDGER_NAME, region_name=None, endpoint_url=None, boto3_session=None):
       """
       Create a QLDB driver for executing transactions.
   
       :type ledger_name: str
       :param ledger_name: The QLDB ledger name.
   
       :type region_name: str
       :param region_name: See [1].
   
       :type endpoint_url: str
       :param endpoint_url: See [1].
   
       :type boto3_session: :py:class:`boto3.session.Session`
       :param boto3_session: The boto3 session to create the client with (see [1]).
   
       :rtype: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :return: A QLDB driver object.
   
       [1]: `Boto3 Session.client Reference <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/core/session.html#boto3.session.Session.client>`.
       """
       qldb_driver = QldbDriver(ledger_name=ledger_name, region_name=region_name, endpoint_url=endpoint_url,
                                boto3_session=boto3_session)
       return qldb_driver
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Connect to a given ledger using default settings.
       """
       try:
           with create_qldb_driver(ledger_name) as driver:
               logger.info('Listing table names ')
               for table in driver.list_tables():
                   logger.info(table)
       except ClientError as ce:
           logger.exception('Unable to list tables.')
           raise ce
   
   
   if __name__ == '__main__':
       main()
   ```

**참고**  
원장에서 데이터 트랜잭션을 실행하려면 특정 원장에 연결할 QLDB 드라이버 객체를 생성해야 합니다. 이는 이전 단계에서 원장을 생성할 때 사용한 `qldb_client` 객체와는 다른 클라이언트 객체입니다. 이전 클라이언트는 [Amazon QLDB API 참조](api-reference.md)에 나열된 관리 API 작업을 실행하는 데만 사용됩니다.
이 드라이버 객체를 생성할 때 원장 이름을 지정해야 합니다.

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from botocore.exceptions import ClientError
   
   from pyqldb.driver.pooled_qldb_driver import PooledQldbDriver
   from pyqldbsamples.constants import Constants
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def create_qldb_driver(ledger_name=Constants.LEDGER_NAME, region_name=None, endpoint_url=None, boto3_session=None):
       """
       Create a QLDB driver for creating sessions.
   
       :type ledger_name: str
       :param ledger_name: The QLDB ledger name.
   
       :type region_name: str
       :param region_name: See [1].
   
       :type endpoint_url: str
       :param endpoint_url: See [1].
   
       :type boto3_session: :py:class:`boto3.session.Session`
       :param boto3_session: The boto3 session to create the client with (see [1]).
   
       :rtype: :py:class:`pyqldb.driver.pooled_qldb_driver.PooledQldbDriver`
       :return: A pooled QLDB driver object.
   
       [1]: `Boto3 Session.client Reference <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/core/session.html#boto3.session.Session.client>`.
       """
       qldb_driver = PooledQldbDriver(ledger_name=ledger_name, region_name=region_name, endpoint_url=endpoint_url,
                                      boto3_session=boto3_session)
       return qldb_driver
   
   
   def create_qldb_session():
       """
       Retrieve a QLDB session object.
   
       :rtype: :py:class:`pyqldb.session.pooled_qldb_session.PooledQldbSession`
       :return: A pooled QLDB session object.
       """
       qldb_session = pooled_qldb_driver.get_session()
       return qldb_session
   
   
   pooled_qldb_driver = create_qldb_driver()
   
   
   if __name__ == '__main__':
       """
       Connect to a session for a given ledger using default settings.
       """
       try:
           qldb_session = create_qldb_session()
           logger.info('Listing table names ')
           for table in qldb_session.list_tables():
               logger.info(table)
       except ClientError:
           logger.exception('Unable to create session.')
   ```

**참고**  
원장에서 데이터 트랜잭션을 실행하려면 특정 원장에 연결할 QLDB 드라이버 객체를 생성해야 합니다. 이는 이전 단계에서 원장을 생성할 때 사용한 `qldb_client` 객체와는 다른 클라이언트 객체입니다. 이전 클라이언트는 [Amazon QLDB API 참조](api-reference.md)에 나열된 관리 API 작업을 실행하는 데만 사용됩니다.
먼저 풀링된 QLDB 드라이버 객체를 생성합니다. 이 드라이버를 생성할 때 원장 이름을 지정해야 합니다.
그러면 이 풀링된 드라이버 객체에서 세션을 생성할 수 있습니다.

------

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python connect_to_ledger.py
   ```

`vehicle-registration` 원장에 테이블을 생성하려면 [3단계: 테이블, 인덱스 및 샘플 데이터 생성](getting-started.python.step-3.md)로 진행하세요.

# 3단계: 테이블, 인덱스 및 샘플 데이터 생성
<a name="getting-started.python.step-3"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB 원장이 활성화되고 연결을 수락하면 차량, 소유자 및 등록 정보에 대한 데이터 테이블 생성을 시작할 수 있습니다. 테이블과 인덱스를 생성한 후 데이터를 로드할 수 있습니다.

이 단계에서는 `vehicle-registration` 원장에 4개의 테이블을 생성합니다.
+ `VehicleRegistration`
+ `Vehicle`
+ `Person`
+ `DriversLicense`

또한 다음과 같은 인덱스를 생성합니다.


****  

| 테이블 이름 | 필드 | 
| --- | --- | 
| VehicleRegistration | VIN | 
| VehicleRegistration | LicensePlateNumber | 
| Vehicle | VIN | 
| Person | GovId | 
| DriversLicense | LicenseNumber | 
| DriversLicense | PersonId | 

샘플 데이터를 삽입할 때는 먼저 `Person` 테이블에 문서를 삽입합니다. 그런 다음 각 `Person` 문서에서 시스템이 할당한 `id`를 사용하여 적절한 `VehicleRegistration` 및 `DriversLicense` 문서의 해당 필드를 채웁니다.

**작은 정보**  
가장 좋은 방법은 문서의 시스템 할당 `id`를 외래 키로 사용하는 것입니다. 고유 식별자(예: 차량의 VIN)로 사용되는 필드를 정의할 수 있지만 문서의 실제  고유 식별자는 `id`입니다. 이 필드는 문서의 메타데이터에 포함되며 *커밋된 뷰*(테이블의 시스텀 정의 뷰)에서 쿼리할 수 있습니다.  
QLDB 뷰에 대한 자세한 내용은 [핵심 개념](ledger-structure.md) 섹션을 참조하세요. 메타데이터에 대해 자세히 알아보려면 [문서 메타데이터 쿼리](working.metadata.md) 섹션을 참조하세요.

**테이블 및 인덱스를 생성하려면**

1. 다음 프로그램(`create_table.py`)을 사용하여 앞서 언급한 테이블을 생성합니다.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def create_table(driver, table_name):
       """
       Create a table with the specified name.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type table_name: str
       :param table_name: Name of the table to create.
   
       :rtype: int
       :return: The number of changes to the database.
       """
       logger.info("Creating the '{}' table...".format(table_name))
       statement = 'CREATE TABLE {}'.format(table_name)
       cursor = driver.execute_lambda(lambda executor: executor.execute_statement(statement))
       logger.info('{} table created successfully.'.format(table_name))
       return len(list(cursor))
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Create registrations, vehicles, owners, and licenses tables.
       """
       try:
           with create_qldb_driver(ledger_name) as driver:
               create_table(driver, Constants.DRIVERS_LICENSE_TABLE_NAME)
               create_table(driver, Constants.PERSON_TABLE_NAME)
               create_table(driver, Constants.VEHICLE_TABLE_NAME)
               create_table(driver, Constants.VEHICLE_REGISTRATION_TABLE_NAME)
               logger.info('Tables created successfully.')
       except Exception as e:
           logger.exception('Errors creating tables.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def create_table(transaction_executor, table_name):
       """
       Create a table with the specified name using an Executor object.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type table_name: str
       :param table_name: Name of the table to create.
   
       :rtype: int
       :return: The number of changes to the database.
       """
       logger.info("Creating the '{}' table...".format(table_name))
       statement = 'CREATE TABLE {}'.format(table_name)
       cursor = transaction_executor.execute_statement(statement)
       logger.info('{} table created successfully.'.format(table_name))
       return len(list(cursor))
   
   
   if __name__ == '__main__':
       """
       Create registrations, vehicles, owners, and licenses tables in a single transaction.
       """
       try:
           with create_qldb_session() as session:
               session.execute_lambda(lambda x: create_table(x, Constants.DRIVERS_LICENSE_TABLE_NAME) and
                                      create_table(x, Constants.PERSON_TABLE_NAME) and
                                      create_table(x, Constants.VEHICLE_TABLE_NAME) and
                                      create_table(x, Constants.VEHICLE_REGISTRATION_TABLE_NAME),
                                      lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
               logger.info('Tables created successfully.')
       except Exception:
           logger.exception('Errors creating tables.')
   ```

------
**참고**  
이 프로그램은 `execute_lambda` 함수의 사용 방법을 설명합니다. 이 예제에서는 단일 Lambda 표현식을 사용하여 여러 `CREATE TABLE` PartiQL 문을 실행합니다.  
이 실행 함수는 암시적으로 트랜잭션을 시작하고 Lambda에서 모든 문을 실행한 다음 트랜잭션을 자동 커밋합니다.

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python create_table.py
   ```

1. 앞에서 설명한 대로 다음 프로그램(`create_index.py`)을 사용하여 테이블에 인덱스를 생성합니다.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def create_index(driver, table_name, index_attribute):
       """
       Create an index for a particular table.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type table_name: str
       :param table_name: Name of the table to add indexes for.
   
       :type index_attribute: str
       :param index_attribute: Index to create on a single attribute.
   
       :rtype: int
       :return: The number of changes to the database.
       """
       logger.info("Creating index on '{}'...".format(index_attribute))
       statement = 'CREATE INDEX on {} ({})'.format(table_name, index_attribute)
       cursor = driver.execute_lambda(lambda executor: executor.execute_statement(statement))
       return len(list(cursor))
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Create indexes on tables in a particular ledger.
       """
       logger.info('Creating indexes on all tables...')
       try:
           with create_qldb_driver(ledger_name) as driver:
               create_index(driver, Constants.PERSON_TABLE_NAME, Constants.GOV_ID_INDEX_NAME)
               create_index(driver, Constants.VEHICLE_TABLE_NAME, Constants.VEHICLE_VIN_INDEX_NAME)
               create_index(driver, Constants.VEHICLE_REGISTRATION_TABLE_NAME, Constants.LICENSE_PLATE_NUMBER_INDEX_NAME)
               create_index(driver, Constants.VEHICLE_REGISTRATION_TABLE_NAME, Constants.VEHICLE_VIN_INDEX_NAME)
               create_index(driver, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.PERSON_ID_INDEX_NAME)
               create_index(driver, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.LICENSE_NUMBER_INDEX_NAME)
               logger.info('Indexes created successfully.')
       except Exception as e:
           logger.exception('Unable to create indexes.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def create_index(transaction_executor, table_name, index_attribute):
       """
       Create an index for a particular table.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type table_name: str
       :param table_name: Name of the table to add indexes for.
   
       :type index_attribute: str
       :param index_attribute: Index to create on a single attribute.
   
       :rtype: int
       :return: The number of changes to the database.
       """
       logger.info("Creating index on '{}'...".format(index_attribute))
       statement = 'CREATE INDEX on {} ({})'.format(table_name, index_attribute)
       cursor = transaction_executor.execute_statement(statement)
       return len(list(cursor))
   
   
   if __name__ == '__main__':
       """
       Create indexes on tables in a particular ledger.
       """
       logger.info('Creating indexes on all tables in a single transaction...')
       try:
           with create_qldb_session() as session:
               session.execute_lambda(lambda x: create_index(x, Constants.PERSON_TABLE_NAME,
                                                             Constants.GOV_ID_INDEX_NAME)
                                      and create_index(x, Constants.VEHICLE_TABLE_NAME,
                                                       Constants.VEHICLE_VIN_INDEX_NAME)
                                      and create_index(x, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                                                       Constants.LICENSE_PLATE_NUMBER_INDEX_NAME)
                                      and create_index(x, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                                                       Constants.VEHICLE_VIN_INDEX_NAME)
                                      and create_index(x, Constants.DRIVERS_LICENSE_TABLE_NAME,
                                                       Constants.PERSON_ID_INDEX_NAME)
                                      and create_index(x, Constants.DRIVERS_LICENSE_TABLE_NAME,
                                                       Constants.LICENSE_NUMBER_INDEX_NAME),
                                      lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
               logger.info('Indexes created successfully.')
       except Exception:
           logger.exception('Unable to create indexes.')
   ```

------

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python create_index.py
   ```

**데이터를 테이블로 로드하려면**

1. `vehicle-registration` 테이블에 삽입한 샘플 데이터를 나타내는 다음 파일(`sample_data.py`)을 검토하세요. 또한 이 파일은 `amazon.ion` 패키지에서 가져와서 [Amazon Ion](ion.md) 데이터를 변환, 구문 분석 및 인쇄하는 도우미 함수를 제공합니다.

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   from datetime import datetime
   from decimal import Decimal
   from logging import basicConfig, getLogger, INFO
   
   from amazon.ion.simple_types import IonPyBool, IonPyBytes, IonPyDecimal, IonPyDict, IonPyFloat, IonPyInt, IonPyList, \
       IonPyNull, IonPySymbol, IonPyText, IonPyTimestamp
   from amazon.ion.simpleion import dumps, loads
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   IonValue = (IonPyBool, IonPyBytes, IonPyDecimal, IonPyDict, IonPyFloat, IonPyInt, IonPyList, IonPyNull, IonPySymbol,
               IonPyText, IonPyTimestamp)
   
   
   class SampleData:
       """
       Sample domain objects for use throughout this tutorial.
       """
       DRIVERS_LICENSE = [
           {
               'PersonId': '',
               'LicenseNumber': 'LEWISR261LL',
               'LicenseType': 'Learner',
               'ValidFromDate': datetime(2016, 12, 20),
               'ValidToDate': datetime(2020, 11, 15)
           },
           {
               'PersonId': '',
               'LicenseNumber': 'LOGANB486CG',
               'LicenseType': 'Probationary',
               'ValidFromDate': datetime(2016, 4, 6),
               'ValidToDate': datetime(2020, 11, 15)
           },
           {
               'PersonId': '',
               'LicenseNumber': '744 849 301',
               'LicenseType': 'Full',
               'ValidFromDate': datetime(2017, 12, 6),
               'ValidToDate': datetime(2022, 10, 15)
           },
           {
               'PersonId': '',
               'LicenseNumber': 'P626-168-229-765',
               'LicenseType': 'Learner',
               'ValidFromDate': datetime(2017, 8, 16),
               'ValidToDate': datetime(2021, 11, 15)
           },
           {
               'PersonId': '',
               'LicenseNumber': 'S152-780-97-415-0',
               'LicenseType': 'Probationary',
               'ValidFromDate': datetime(2015, 8, 15),
               'ValidToDate': datetime(2021, 8, 21)
           }
       ]
       PERSON = [
           {
               'FirstName': 'Raul',
               'LastName': 'Lewis',
               'Address': '1719 University Street, Seattle, WA, 98109',
               'DOB': datetime(1963, 8, 19),
               'GovId': 'LEWISR261LL',
               'GovIdType': 'Driver License'
           },
           {
               'FirstName': 'Brent',
               'LastName': 'Logan',
               'DOB': datetime(1967, 7, 3),
               'Address': '43 Stockert Hollow Road, Everett, WA, 98203',
               'GovId': 'LOGANB486CG',
               'GovIdType': 'Driver License'
           },
           {
               'FirstName': 'Alexis',
               'LastName': 'Pena',
               'DOB': datetime(1974, 2, 10),
               'Address': '4058 Melrose Street, Spokane Valley, WA, 99206',
               'GovId': '744 849 301',
               'GovIdType': 'SSN'
           },
           {
               'FirstName': 'Melvin',
               'LastName': 'Parker',
               'DOB': datetime(1976, 5, 22),
               'Address': '4362 Ryder Avenue, Seattle, WA, 98101',
               'GovId': 'P626-168-229-765',
               'GovIdType': 'Passport'
           },
           {
               'FirstName': 'Salvatore',
               'LastName': 'Spencer',
               'DOB': datetime(1997, 11, 15),
               'Address': '4450 Honeysuckle Lane, Seattle, WA, 98101',
               'GovId': 'S152-780-97-415-0',
               'GovIdType': 'Passport'
           }
       ]
       VEHICLE = [
           {
               'VIN': '1N4AL11D75C109151',
               'Type': 'Sedan',
               'Year': 2011,
               'Make': 'Audi',
               'Model': 'A5',
               'Color': 'Silver'
           },
           {
               'VIN': 'KM8SRDHF6EU074761',
               'Type': 'Sedan',
               'Year': 2015,
               'Make': 'Tesla',
               'Model': 'Model S',
               'Color': 'Blue'
           },
           {
               'VIN': '3HGGK5G53FM761765',
               'Type': 'Motorcycle',
               'Year': 2011,
               'Make': 'Ducati',
               'Model': 'Monster 1200',
               'Color': 'Yellow'
           },
           {
               'VIN': '1HVBBAANXWH544237',
               'Type': 'Semi',
               'Year': 2009,
               'Make': 'Ford',
               'Model': 'F 150',
               'Color': 'Black'
           },
           {
               'VIN': '1C4RJFAG0FC625797',
               'Type': 'Sedan',
               'Year': 2019,
               'Make': 'Mercedes',
               'Model': 'CLK 350',
               'Color': 'White'
           }
       ]
       VEHICLE_REGISTRATION = [
           {
               'VIN': '1N4AL11D75C109151',
               'LicensePlateNumber': 'LEWISR261LL',
               'State': 'WA',
               'City': 'Seattle',
               'ValidFromDate': datetime(2017, 8, 21),
               'ValidToDate': datetime(2020, 5, 11),
               'PendingPenaltyTicketAmount': Decimal('90.25'),
               'Owners': {
                   'PrimaryOwner': {'PersonId': ''},
                   'SecondaryOwners': []
               }
           },
           {
               'VIN': 'KM8SRDHF6EU074761',
               'LicensePlateNumber': 'CA762X',
               'State': 'WA',
               'City': 'Kent',
               'PendingPenaltyTicketAmount': Decimal('130.75'),
               'ValidFromDate': datetime(2017, 9, 14),
               'ValidToDate': datetime(2020, 6, 25),
               'Owners': {
                   'PrimaryOwner': {'PersonId': ''},
                   'SecondaryOwners': []
               }
           },
           {
               'VIN': '3HGGK5G53FM761765',
               'LicensePlateNumber': 'CD820Z',
               'State': 'WA',
               'City': 'Everett',
               'PendingPenaltyTicketAmount': Decimal('442.30'),
               'ValidFromDate': datetime(2011, 3, 17),
               'ValidToDate': datetime(2021, 3, 24),
               'Owners': {
                   'PrimaryOwner': {'PersonId': ''},
                   'SecondaryOwners': []
               }
           },
           {
               'VIN': '1HVBBAANXWH544237',
               'LicensePlateNumber': 'LS477D',
               'State': 'WA',
               'City': 'Tacoma',
               'PendingPenaltyTicketAmount': Decimal('42.20'),
               'ValidFromDate': datetime(2011, 10, 26),
               'ValidToDate': datetime(2023, 9, 25),
               'Owners': {
                   'PrimaryOwner': {'PersonId': ''},
                   'SecondaryOwners': []
               }
           },
           {
               'VIN': '1C4RJFAG0FC625797',
               'LicensePlateNumber': 'TH393F',
               'State': 'WA',
               'City': 'Olympia',
               'PendingPenaltyTicketAmount': Decimal('30.45'),
               'ValidFromDate': datetime(2013, 9, 2),
               'ValidToDate': datetime(2024, 3, 19),
               'Owners': {
                   'PrimaryOwner': {'PersonId': ''},
                   'SecondaryOwners': []
               }
           }
       ]
   
   
   def convert_object_to_ion(py_object):
       """
       Convert a Python object into an Ion object.
   
       :type py_object: object
       :param py_object: The object to convert.
   
       :rtype: :py:class:`amazon.ion.simple_types.IonPyValue`
       :return: The converted Ion object.
       """
       ion_object = loads(dumps(py_object))
       return ion_object
   
   
   def to_ion_struct(key, value):
       """
       Convert the given key and value into an Ion struct.
   
       :type key: str
       :param key: The key which serves as an unique identifier.
   
       :type value: str
       :param value: The value associated with a given key.
   
       :rtype: :py:class:`amazon.ion.simple_types.IonPyDict`
       :return: The Ion dictionary object.
       """
       ion_struct = dict()
       ion_struct[key] = value
       return loads(str(ion_struct))
   
   
   def get_document_ids(transaction_executor, table_name, field, value):
       """
       Gets the document IDs from the given table.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type table_name: str
       :param table_name: The table name to query.
   
       :type field: str
       :param field: A field to query.
   
       :type value: str
       :param value: The key of the given field.
   
       :rtype: list
       :return: A list of document IDs.
       """
       query = "SELECT id FROM {} AS t BY id WHERE t.{} = ?".format(table_name, field)
       cursor = transaction_executor.execute_statement(query, convert_object_to_ion(value))
       return list(map(lambda table: table.get('id'), cursor))
   
   
   def get_document_ids_from_dml_results(result):
       """
       Return a list of modified document IDs as strings from DML results.
   
       :type result: :py:class:`pyqldb.cursor.buffered_cursor.BufferedCursor`
       :param: result: The result set from DML operation.
   
       :rtype: list
       :return: List of document IDs.
       """
       ret_val = list(map(lambda x: x.get('documentId'), result))
       return ret_val
   
   
   def print_result(cursor):
       """
       Pretty print the result set. Returns the number of documents in the result set.
   
       :type cursor: :py:class:`pyqldb.cursor.stream_cursor.StreamCursor`/
                     :py:class:`pyqldb.cursor.buffered_cursor.BufferedCursor`
       :param cursor: An instance of the StreamCursor or BufferedCursor class.
   
       :rtype: int
       :return: Number of documents in the result set.
       """
       result_counter = 0
       for row in cursor:
           # Each row would be in Ion format.
           print_ion(row)
           result_counter += 1
       return result_counter
   
   
   def print_ion(ion_value):
       """
       Pretty print an Ion Value.
   
       :type ion_value: :py:class:`amazon.ion.simple_types.IonPySymbol`
       :param ion_value: Any Ion Value to be pretty printed.
       """
       logger.info(dumps(ion_value, binary=False, indent='  ', omit_version_marker=True))
   ```
**참고**  
이 `get_document_ids` 함수는 테이블에서 시스템 할당 문서 ID를 반환하는 쿼리를 실행합니다. 자세한 내용은 [BY 절을 사용하여 문서 ID 쿼리하기](working.metadata.by-clause.md) 섹션을 참조하세요.

1. 다음 프로그램(`insert_document.py`)을 사용하여 샘플 데이터를 테이블에 삽입합니다.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.model.sample_data import convert_object_to_ion, SampleData, get_document_ids_from_dml_results
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def update_person_id(document_ids):
       """
       Update the PersonId value for DriversLicense records and the PrimaryOwner value for VehicleRegistration records.
   
       :type document_ids: list
       :param document_ids: List of document IDs.
   
       :rtype: list
       :return: Lists of updated DriversLicense records and updated VehicleRegistration records.
       """
       new_drivers_licenses = SampleData.DRIVERS_LICENSE.copy()
       new_vehicle_registrations = SampleData.VEHICLE_REGISTRATION.copy()
       for i in range(len(SampleData.PERSON)):
           drivers_license = new_drivers_licenses[i]
           registration = new_vehicle_registrations[i]
           drivers_license.update({'PersonId': str(document_ids[i])})
           registration['Owners']['PrimaryOwner'].update({'PersonId': str(document_ids[i])})
       return new_drivers_licenses, new_vehicle_registrations
   
   
   def insert_documents(driver, table_name, documents):
       """
       Insert the given list of documents into a table in a single transaction.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type table_name: str
       :param table_name: Name of the table to insert documents into.
   
       :type documents: list
       :param documents: List of documents to insert.
   
       :rtype: list
       :return: List of documents IDs for the newly inserted documents.
       """
       logger.info('Inserting some documents in the {} table...'.format(table_name))
       statement = 'INSERT INTO {} ?'.format(table_name)
       cursor = driver.execute_lambda(lambda executor: executor.execute_statement(statement,
                                                                                  convert_object_to_ion(documents)))
       list_of_document_ids = get_document_ids_from_dml_results(cursor)
   
       return list_of_document_ids
   
   
   def update_and_insert_documents(driver):
       """
       Handle the insertion of documents and updating PersonIds.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
       """
       list_ids = insert_documents(driver, Constants.PERSON_TABLE_NAME, SampleData.PERSON)
   
       logger.info("Updating PersonIds for 'DriversLicense' and PrimaryOwner for 'VehicleRegistration'...")
       new_licenses, new_registrations = update_person_id(list_ids)
   
       insert_documents(driver, Constants.VEHICLE_TABLE_NAME, SampleData.VEHICLE)
       insert_documents(driver, Constants.VEHICLE_REGISTRATION_TABLE_NAME, new_registrations)
       insert_documents(driver, Constants.DRIVERS_LICENSE_TABLE_NAME, new_licenses)
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Insert documents into a table in a QLDB ledger.
       """
       try:
           with create_qldb_driver(ledger_name) as driver:
               # An INSERT statement creates the initial revision of a document with a version number of zero.
               # QLDB also assigns a unique document identifier in GUID format as part of the metadata.
               update_and_insert_documents(driver)
               logger.info('Documents inserted successfully!')
       except Exception as e:
           logger.exception('Error inserting or updating documents.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.model.sample_data import convert_object_to_ion, SampleData, get_document_ids_from_dml_results
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def update_person_id(document_ids):
       """
       Update the PersonId value for DriversLicense records and the PrimaryOwner value for VehicleRegistration records.
   
       :type document_ids: list
       :param document_ids: List of document IDs.
   
       :rtype: list
       :return: Lists of updated DriversLicense records and updated VehicleRegistration records.
       """
       new_drivers_licenses = SampleData.DRIVERS_LICENSE.copy()
       new_vehicle_registrations = SampleData.VEHICLE_REGISTRATION.copy()
       for i in range(len(SampleData.PERSON)):
           drivers_license = new_drivers_licenses[i]
           registration = new_vehicle_registrations[i]
           drivers_license.update({'PersonId': str(document_ids[i])})
           registration['Owners']['PrimaryOwner'].update({'PersonId': str(document_ids[i])})
       return new_drivers_licenses, new_vehicle_registrations
   
   
   def insert_documents(transaction_executor, table_name, documents):
       """
       Insert the given list of documents into a table in a single transaction.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type table_name: str
       :param table_name: Name of the table to insert documents into.
   
       :type documents: list
       :param documents: List of documents to insert.
   
       :rtype: list
       :return: List of documents IDs for the newly inserted documents.
       """
       logger.info('Inserting some documents in the {} table...'.format(table_name))
       statement = 'INSERT INTO {} ?'.format(table_name)
       cursor = transaction_executor.execute_statement(statement, convert_object_to_ion(documents))
       list_of_document_ids = get_document_ids_from_dml_results(cursor)
   
       return list_of_document_ids
   
   
   def update_and_insert_documents(transaction_executor):
       """
       Handle the insertion of documents and updating PersonIds all in a single transaction.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
       """
       list_ids = insert_documents(transaction_executor, Constants.PERSON_TABLE_NAME, SampleData.PERSON)
   
       logger.info("Updating PersonIds for 'DriversLicense' and PrimaryOwner for 'VehicleRegistration'...")
       new_licenses, new_registrations = update_person_id(list_ids)
   
       insert_documents(transaction_executor, Constants.VEHICLE_TABLE_NAME, SampleData.VEHICLE)
       insert_documents(transaction_executor, Constants.VEHICLE_REGISTRATION_TABLE_NAME, new_registrations)
       insert_documents(transaction_executor, Constants.DRIVERS_LICENSE_TABLE_NAME, new_licenses)
   
   
   if __name__ == '__main__':
       """
       Insert documents into a table in a QLDB ledger.
       """
       try:
           with create_qldb_session() as session:
               # An INSERT statement creates the initial revision of a document with a version number of zero.
               # QLDB also assigns a unique document identifier in GUID format as part of the metadata.
               session.execute_lambda(lambda executor: update_and_insert_documents(executor),
                                      lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
               logger.info('Documents inserted successfully!')
       except Exception:
           logger.exception('Error inserting or updating documents.')
   ```

------
**참고**  
이 프로그램은 파라미터화된 값을 사용하여 `execute_statement` 함수를 호출하는 방법을 보여줍니다. 실행하려는 PartiQL 문 외에도 데이터 파라미터를 전달할 수 있습니다. 명령문 문자열에서 물음표(`?`)를 변수 자리 표시자로 사용하세요.
`INSERT` 문이 성공하면 삽입된 각 문서의 `id`이 반환됩니다.

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python insert_document.py
   ```

다음으로 `SELECT` 문을 사용하여 `vehicle-registration` 원장의 테이블에서 데이터를 읽을 수 있습니다. [4단계: 원장에서 테이블 쿼리](getting-started.python.step-4.md)로 이동합니다.

# 4단계: 원장에서 테이블 쿼리
<a name="getting-started.python.step-4"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB 원장에 테이블을 생성하고 데이터를 로드한 후 쿼리를 실행하여 방금 삽입한 차량 등록 데이터를 검토할 수 있습니다. QLDB는 [PartiQL](ql-reference.md)을 쿼리 언어로 사용하고 [Amazon Ion](ion.md)을 문서 지향 데이터 모델로 사용합니다.

PartiQL은 Ion과 함께 작동하도록 확장된 오픈 소스 SQL 호환 쿼리 언어입니다. PartiQL을 사용하면 익숙한 SQL 연산자를 사용하여 데이터를 삽입, 쿼리 및 관리할 수 있습니다. Amazon Ion은 JSON의 상위 집합입니다. Ion은 정형, 반정형 및 중첩 데이터를 저장하고 처리할 수 있는 유연성을 제공하는 오픈 소스 문서 기반 데이터 형식입니다.

이 단계에서는 `SELECT` 명령문을 사용하여 `vehicle-registration` 원장의 테이블에서 데이터를 읽습니다.

**주의**  
인덱싱된 조회 없이 QLDB에서 쿼리를 실행하면 전체 테이블 스캔이 호출됩니다. PartiQL은 SQL과 호환되므로 이러한 쿼리를 지원합니다. 하지만 QLDB의 프로덕션 사용 사례에 대해서는 테이블 스캔을 실행하지 *마세요.*. 테이블 스캔은 동시성 충돌 및 트랜잭션 시간 초과를 포함하여 대규모 테이블에서 성능 문제를 일으킬 수 있습니다.  
인덱싱된 필드 또는 문서 ID(예: `WHERE indexedField = 123` 또는 `WHERE indexedField IN (456, 789)`)에서 동등 *연산자*를 사용하여 `WHERE` 조건자 절이 포함된 문을 실행하는 것이 좋습니다. 자세한 내용은 [쿼리 성능 최적화](working.optimize.md)을 참조하세요.

**테이블을 쿼리하려면**

1. 다음 프로그램(`find_vehicles.py`)을 사용하여 원장에 있는 사람의 이름으로 등록된 모든 차량을 쿼리하세요.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import get_document_ids, print_result, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def find_vehicles_for_owner(driver, gov_id):
       """
       Find vehicles registered under a driver using their government ID.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type gov_id: str
       :param gov_id: The owner's government ID.
       """
       document_ids = driver.execute_lambda(lambda executor: get_document_ids(executor, Constants.PERSON_TABLE_NAME,
                                                                              'GovId', gov_id))
   
       query = "SELECT Vehicle FROM Vehicle INNER JOIN VehicleRegistration AS r " \
               "ON Vehicle.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?"
   
       for ids in document_ids:
           cursor = driver.execute_lambda(lambda executor: executor.execute_statement(query, ids))
           logger.info('List of Vehicles for owner with GovId: {}...'.format(gov_id))
           print_result(cursor)
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Find all vehicles registered under a person.
       """
       try:
           with create_qldb_driver(ledger_name) as driver:
               # Find all vehicles registered under a person.
               gov_id = SampleData.PERSON[0]['GovId']
               find_vehicles_for_owner(driver, gov_id)
       except Exception as e:
           logger.exception('Error getting vehicles for owner.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import get_document_ids, print_result, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def find_vehicles_for_owner(transaction_executor, gov_id):
       """
       Find vehicles registered under a driver using their government ID.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type gov_id: str
       :param gov_id: The owner's government ID.
       """
       document_ids = get_document_ids(transaction_executor, Constants.PERSON_TABLE_NAME, 'GovId', gov_id)
   
       query = "SELECT Vehicle FROM Vehicle INNER JOIN VehicleRegistration AS r " \
               "ON Vehicle.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?"
   
       for ids in document_ids:
           cursor = transaction_executor.execute_statement(query, ids)
           logger.info('List of Vehicles for owner with GovId: {}...'.format(gov_id))
           print_result(cursor)
   
   
   if __name__ == '__main__':
       """
       Find all vehicles registered under a person.
       """
       try:
           with create_qldb_session() as session:
               # Find all vehicles registered under a person.
               gov_id = SampleData.PERSON[0]['GovId']
               session.execute_lambda(lambda executor: find_vehicles_for_owner(executor, gov_id),
                                      lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
       except Exception:
           logger.exception('Error getting vehicles for owner.')
   ```

------
**참고**  
먼저 이 프로그램은 이 문서에 대한 `Person` 테이블을 `GovId LEWISR261LL`로 쿼리하여 `id` 메타데이터 필드를 가져옵니다.  
그런 다음 이 문서 `id`를 외래 키로 사용하여 `VehicleRegistration` 테이블을 `PrimaryOwner.PersonId`로 쿼리합니다. 또한 `VIN` 필드의 `Vehicle` 테이블과 `VehicleRegistration`를 조인합니다.

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python find_vehicles.py
   ```

`vehicle-registration` 원장의 테이블에 있는 문서를 수정하는 방법에 대한 자세한 내용은 [5단계: 원장의 문서 수정](getting-started.python.step-5.md)을 참조하세요.

# 5단계: 원장의 문서 수정
<a name="getting-started.python.step-5"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이제 작업할 데이터가 있으므로 Amazon QLDB에서 `vehicle-registration` 원장에 있는 문서를 변경할 수 있습니다. 이 단계에서 다음 코드 예제는 DML(데이터 조작 언어) 문을 실행하는 방법을 보여줍니다. 이러한 명령문은 한 차량의 주 소유자를 업데이트하고 다른 차량에 보조 소유자를 추가합니다.

**문서를 수정하려면**

1. 다음 프로그램(`transfer_vehicle_ownership.py`)을 사용하여 차량의 주 소유자를 원장에 VIN `1N4AL11D75C109151`으로 업데이트하세요.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.add_secondary_owner import get_document_ids, print_result, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.model.sample_data import convert_object_to_ion
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def find_person_from_document_id(transaction_executor, document_id):
       """
       Query a driver's information using the given ID.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type document_id: :py:class:`amazon.ion.simple_types.IonPyText`
       :param document_id: The document ID required to query for the person.
   
       :rtype: :py:class:`amazon.ion.simple_types.IonPyDict`
       :return: The resulting document from the query.
       """
       query = 'SELECT p.* FROM Person AS p BY pid WHERE pid = ?'
       cursor = transaction_executor.execute_statement(query, document_id)
       return next(cursor)
   
   
   def find_primary_owner_for_vehicle(driver, vin):
       """
       Find the primary owner of a vehicle given its VIN.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: The VIN to find primary owner for.
   
       :rtype: :py:class:`amazon.ion.simple_types.IonPyDict`
       :return: The resulting document from the query.
       """
       logger.info('Finding primary owner for vehicle with VIN: {}.'.format(vin))
       query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?"
       cursor = driver.execute_lambda(lambda executor: executor.execute_statement(query, convert_object_to_ion(vin)))
       try:
           return driver.execute_lambda(lambda executor: find_person_from_document_id(executor,
                                                                                      next(cursor).get('PersonId')))
       except StopIteration:
           logger.error('No primary owner registered for this vehicle.')
           return None
   
   
   def update_vehicle_registration(driver, vin, document_id):
       """
       Update the primary owner for a vehicle using the given VIN.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: The VIN for the vehicle to operate on.
   
       :type document_id: :py:class:`amazon.ion.simple_types.IonPyText`
       :param document_id: New PersonId for the primary owner.
   
       :raises RuntimeError: If no vehicle registration was found using the given document ID and VIN.
       """
       logger.info('Updating the primary owner for vehicle with Vin: {}...'.format(vin))
       statement = "UPDATE VehicleRegistration AS r SET r.Owners.PrimaryOwner.PersonId = ? WHERE r.VIN = ?"
       cursor = driver.execute_lambda(lambda executor: executor.execute_statement(statement, document_id,
                                                                                  convert_object_to_ion(vin)))
       try:
           print_result(cursor)
           logger.info('Successfully transferred vehicle with VIN: {} to new owner.'.format(vin))
       except StopIteration:
           raise RuntimeError('Unable to transfer vehicle, could not find registration.')
   
   
   def validate_and_update_registration(driver, vin, current_owner, new_owner):
       """
       Validate the current owner of the given vehicle and transfer its ownership to a new owner.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: The VIN of the vehicle to transfer ownership of.
   
       :type current_owner: str
       :param current_owner: The GovId of the current owner of the vehicle.
   
       :type new_owner: str
       :param new_owner: The GovId of the new owner of the vehicle.
   
       :raises RuntimeError: If unable to verify primary owner.
       """
       primary_owner = find_primary_owner_for_vehicle(driver, vin)
       if primary_owner is None or primary_owner['GovId'] != current_owner:
           raise RuntimeError('Incorrect primary owner identified for vehicle, unable to transfer.')
   
       document_ids = driver.execute_lambda(lambda executor: get_document_ids(executor, Constants.PERSON_TABLE_NAME,
                                                                              'GovId', new_owner))
       update_vehicle_registration(driver, vin, document_ids[0])
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Find primary owner for a particular vehicle's VIN.
       Transfer to another primary owner for a particular vehicle's VIN.
       """
       vehicle_vin = SampleData.VEHICLE[0]['VIN']
       previous_owner = SampleData.PERSON[0]['GovId']
       new_owner = SampleData.PERSON[1]['GovId']
   
       try:
           with create_qldb_driver(ledger_name) as driver:
               validate_and_update_registration(driver, vehicle_vin, previous_owner, new_owner)
       except Exception as e:
           logger.exception('Error updating VehicleRegistration.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.add_secondary_owner import get_document_ids, print_result, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.model.sample_data import convert_object_to_ion
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def find_person_from_document_id(transaction_executor, document_id):
       """
       Query a driver's information using the given ID.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type document_id: :py:class:`amazon.ion.simple_types.IonPyText`
       :param document_id: The document ID required to query for the person.
   
       :rtype: :py:class:`amazon.ion.simple_types.IonPyDict`
       :return: The resulting document from the query.
       """
       query = 'SELECT p.* FROM Person AS p BY pid WHERE pid = ?'
       cursor = transaction_executor.execute_statement(query, document_id)
       return next(cursor)
   
   
   def find_primary_owner_for_vehicle(transaction_executor, vin):
       """
       Find the primary owner of a vehicle given its VIN.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type vin: str
       :param vin: The VIN to find primary owner for.
   
       :rtype: :py:class:`amazon.ion.simple_types.IonPyDict`
       :return: The resulting document from the query.
       """
       logger.info('Finding primary owner for vehicle with VIN: {}.'.format(vin))
       query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?"
       cursor = transaction_executor.execute_statement(query, convert_object_to_ion(vin))
       try:
           return find_person_from_document_id(transaction_executor, next(cursor).get('PersonId'))
       except StopIteration:
           logger.error('No primary owner registered for this vehicle.')
           return None
   
   
   def update_vehicle_registration(transaction_executor, vin, document_id):
       """
       Update the primary owner for a vehicle using the given VIN.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type vin: str
       :param vin: The VIN for the vehicle to operate on.
   
       :type document_id: :py:class:`amazon.ion.simple_types.IonPyText`
       :param document_id: New PersonId for the primary owner.
   
       :raises RuntimeError: If no vehicle registration was found using the given document ID and VIN.
       """
       logger.info('Updating the primary owner for vehicle with Vin: {}...'.format(vin))
       statement = "UPDATE VehicleRegistration AS r SET r.Owners.PrimaryOwner.PersonId = ? WHERE r.VIN = ?"
       cursor = transaction_executor.execute_statement(statement, document_id, convert_object_to_ion(vin))
       try:
           print_result(cursor)
           logger.info('Successfully transferred vehicle with VIN: {} to new owner.'.format(vin))
       except StopIteration:
           raise RuntimeError('Unable to transfer vehicle, could not find registration.')
   
   
   def validate_and_update_registration(transaction_executor, vin, current_owner, new_owner):
       """
       Validate the current owner of the given vehicle and transfer its ownership to a new owner in a single transaction.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type vin: str
       :param vin: The VIN of the vehicle to transfer ownership of.
   
       :type current_owner: str
       :param current_owner: The GovId of the current owner of the vehicle.
   
       :type new_owner: str
       :param new_owner: The GovId of the new owner of the vehicle.
   
       :raises RuntimeError: If unable to verify primary owner.
       """
       primary_owner = find_primary_owner_for_vehicle(transaction_executor, vin)
       if primary_owner is None or primary_owner['GovId'] != current_owner:
           raise RuntimeError('Incorrect primary owner identified for vehicle, unable to transfer.')
   
       document_id = next(get_document_ids(transaction_executor, Constants.PERSON_TABLE_NAME, 'GovId', new_owner))
   
       update_vehicle_registration(transaction_executor, vin, document_id)
   
   
   if __name__ == '__main__':
       """
       Find primary owner for a particular vehicle's VIN.
       Transfer to another primary owner for a particular vehicle's VIN.
       """
       vehicle_vin = SampleData.VEHICLE[0]['VIN']
       previous_owner = SampleData.PERSON[0]['GovId']
       new_owner = SampleData.PERSON[1]['GovId']
   
       try:
           with create_qldb_session() as session:
               session.execute_lambda(lambda executor: validate_and_update_registration(executor, vehicle_vin,
                                                                                        previous_owner, new_owner),
                                      retry_indicator=lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
       except Exception:
           logger.exception('Error updating VehicleRegistration.')
   ```

------

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python transfer_vehicle_ownership.py
   ```

1. 다음 프로그램(`add_secondary_owner.py`)을 사용하여 차량의 보조 소유자를 원장에 VIN `KM8SRDHF6EU074761`으로 추가하세요.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import to_ion_struct, get_document_ids, print_result, SampleData, \
       convert_object_to_ion
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def get_document_id_by_gov_id(driver, government_id):
       """
       Find a driver's person ID using the given government ID.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type government_id: str
       :param government_id: A driver's government ID.
   
       :rtype: list
       :return: A list of document IDs.
       """
       logger.info("Finding secondary owner's person ID using given government ID: {}.".format(government_id))
       return driver.execute_lambda(lambda executor: get_document_ids(executor, Constants.PERSON_TABLE_NAME, 'GovId',
                                                                      government_id))
   
   
   def is_secondary_owner_for_vehicle(driver, vin, secondary_owner_id):
       """
       Check whether a secondary owner has already been registered for the given VIN.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: VIN of the vehicle to query.
   
       :type secondary_owner_id: str
       :param secondary_owner_id: The secondary owner's person ID.
   
       :rtype: bool
       :return: If the driver has already been registered.
       """
       logger.info('Finding secondary owners for vehicle with VIN: {}...'.format(vin))
       query = 'SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?'
       rows = driver.execute_lambda(lambda executor: executor.execute_statement(query, convert_object_to_ion(vin)))
   
       for row in rows:
           secondary_owners = row.get('SecondaryOwners')
           person_ids = map(lambda owner: owner.get('PersonId').text, secondary_owners)
           if secondary_owner_id in person_ids:
               return True
       return False
   
   
   def add_secondary_owner_for_vin(driver, vin, parameter):
       """
       Add a secondary owner into `VehicleRegistration` table for a particular VIN.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: VIN of the vehicle to add a secondary owner for.
   
       :type parameter: :py:class:`amazon.ion.simple_types.IonPyValue`
       :param parameter: The Ion value or Python native type that is convertible to Ion for filling in parameters of the
                         statement.
       """
       logger.info('Inserting secondary owner for vehicle with VIN: {}...'.format(vin))
       statement = "FROM VehicleRegistration AS v WHERE v.VIN = ? INSERT INTO v.Owners.SecondaryOwners VALUE ?"
   
       cursor = driver.execute_lambda(lambda executor: executor.execute_statement(statement, convert_object_to_ion(vin),
                                                                                  parameter))
       logger.info('VehicleRegistration Document IDs which had secondary owners added: ')
       print_result(cursor)
   
   
   def register_secondary_owner(driver, vin, gov_id):
       """
       Register a secondary owner for a vehicle if they are not already registered.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: VIN of the vehicle to register a secondary owner for.
   
       :type gov_id: str
       :param gov_id: The government ID of the owner.
       """
       logger.info('Finding the secondary owners for vehicle with VIN: {}.'.format(vin))
   
       document_ids = get_document_id_by_gov_id(driver, gov_id)
   
       for document_id in document_ids:
           if is_secondary_owner_for_vehicle(driver, vin, document_id):
               logger.info('Person with ID {} has already been added as a secondary owner of this vehicle.'.format(gov_id))
           else:
               add_secondary_owner_for_vin(driver, vin, to_ion_struct('PersonId', document_id))
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Finds and adds secondary owners for a vehicle.
       """
       vin = SampleData.VEHICLE[1]['VIN']
       gov_id = SampleData.PERSON[0]['GovId']
       try:
           with create_qldb_driver(ledger_name) as driver:
               register_secondary_owner(driver, vin, gov_id)
               logger.info('Secondary owners successfully updated.')
       except Exception as e:
           logger.exception('Error adding secondary owner.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import to_ion_struct, get_document_ids, print_result, SampleData, \
       convert_object_to_ion
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def get_document_id_by_gov_id(transaction_executor, government_id):
       """
       Find a driver's person ID using the given government ID.
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
       :type government_id: str
       :param government_id: A driver's government ID.
       :rtype: list
       :return: A list of document IDs.
       """
       logger.info("Finding secondary owner's person ID using given government ID: {}.".format(government_id))
       return get_document_ids(transaction_executor, Constants.PERSON_TABLE_NAME, 'GovId', government_id)
   
   
   def is_secondary_owner_for_vehicle(transaction_executor, vin, secondary_owner_id):
       """
       Check whether a secondary owner has already been registered for the given VIN.
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
       :type vin: str
       :param vin: VIN of the vehicle to query.
       :type secondary_owner_id: str
       :param secondary_owner_id: The secondary owner's person ID.
       :rtype: bool
       :return: If the driver has already been registered.
       """
       logger.info('Finding secondary owners for vehicle with VIN: {}...'.format(vin))
       query = 'SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?'
       rows = transaction_executor.execute_statement(query, convert_object_to_ion(vin))
   
       for row in rows:
           secondary_owners = row.get('SecondaryOwners')
           person_ids = map(lambda owner: owner.get('PersonId').text, secondary_owners)
           if secondary_owner_id in person_ids:
               return True
       return False
   
   
   def add_secondary_owner_for_vin(transaction_executor, vin, parameter):
       """
       Add a secondary owner into `VehicleRegistration` table for a particular VIN.
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
       :type vin: str
       :param vin: VIN of the vehicle to add a secondary owner for.
       :type parameter: :py:class:`amazon.ion.simple_types.IonPyValue`
       :param parameter: The Ion value or Python native type that is convertible to Ion for filling in parameters of the
                         statement.
       """
       logger.info('Inserting secondary owner for vehicle with VIN: {}...'.format(vin))
       statement = "FROM VehicleRegistration AS v WHERE v.VIN = '{}' INSERT INTO v.Owners.SecondaryOwners VALUE ?"\
           .format(vin)
   
       cursor = transaction_executor.execute_statement(statement, parameter)
       logger.info('VehicleRegistration Document IDs which had secondary owners added: ')
       print_result(cursor)
   
   
   def register_secondary_owner(transaction_executor, vin, gov_id):
       """
       Register a secondary owner for a vehicle if they are not already registered.
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
       :type vin: str
       :param vin: VIN of the vehicle to register a secondary owner for.
       :type gov_id: str
       :param gov_id: The government ID of the owner.
       """
       logger.info('Finding the secondary owners for vehicle with VIN: {}.'.format(vin))
       document_ids = get_document_id_by_gov_id(transaction_executor, gov_id)
   
       for document_id in document_ids:
           if is_secondary_owner_for_vehicle(transaction_executor, vin, document_id):
               logger.info('Person with ID {} has already been added as a secondary owner of this vehicle.'.format(gov_id))
           else:
               add_secondary_owner_for_vin(transaction_executor, vin, to_ion_struct('PersonId', document_id))
   
   
   if __name__ == '__main__':
       """
       Finds and adds secondary owners for a vehicle.
       """
       vin = SampleData.VEHICLE[1]['VIN']
       gov_id = SampleData.PERSON[0]['GovId']
       try:
           with create_qldb_session() as session:
               session.execute_lambda(lambda executor: register_secondary_owner(executor, vin, gov_id),
                                      lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
               logger.info('Secondary owners successfully updated.')
       except Exception:
           logger.exception('Error adding secondary owner.')
   ```

------

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python add_secondary_owner.py
   ```

`vehicle-registration` 원장의 이러한 변경 사항을 검토하려면 [6단계: 문서의 개정 기록 보기](getting-started.python.step-6.md)을 참조하세요.

# 6단계: 문서의 개정 기록 보기
<a name="getting-started.python.step-6"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이전 단계에서 차량의 등록 데이터를 수정한 후 등록된 모든 소유자의 기록과 기타 업데이트된 필드를 쿼리할 수 있습니다. 이 단계에서는 `vehicle-registration` 원장의 `VehicleRegistration` 테이블에 있는 문서의 개정 기록을 쿼리합니다.

**개정 기록을 보려면**

1. 다음 프로그램(`query_history.py`)을 사용하여 VIN `1N4AL11D75C109151`로 `VehicleRegistration` 문서의 개정 기록을 쿼리합니다.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from datetime import datetime, timedelta
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import print_result, get_document_ids, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def format_date_time(date_time):
       """
       Format the given date time to a string.
   
       :type date_time: :py:class:`datetime.datetime`
       :param date_time: The date time to format.
   
       :rtype: str
       :return: The formatted date time.
       """
       return date_time.strftime('`%Y-%m-%dT%H:%M:%S.%fZ`')
   
   
   def previous_primary_owners(driver, vin):
       """
       Find previous primary owners for the given VIN in a single transaction.
       In this example, query the `VehicleRegistration` history table to find all previous primary owners for a VIN.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: VIN to find previous primary owners for.
       """
       person_ids = driver.execute_lambda(lambda executor: get_document_ids(executor,
                                                                            Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                                                                            'VIN', vin))
   
       todays_date = datetime.utcnow() - timedelta(seconds=1)
       three_months_ago = todays_date - timedelta(days=90)
       query = 'SELECT data.Owners.PrimaryOwner, metadata.version FROM history({}, {}, {}) AS h WHERE h.metadata.id = ?'.\
           format(Constants.VEHICLE_REGISTRATION_TABLE_NAME, format_date_time(three_months_ago),
                  format_date_time(todays_date))
   
       for ids in person_ids:
           logger.info("Querying the 'VehicleRegistration' table's history using VIN: {}.".format(vin))
           cursor = driver.execute_lambda(lambda executor: executor.execute_statement(query, ids))
           if not (print_result(cursor)) > 0:
               logger.info('No modification history found within the given time frame for document ID: {}'.format(ids))
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Query a table's history for a particular set of documents.
       """
       try:
           with create_qldb_driver(ledger_name) as driver:
               vin = SampleData.VEHICLE_REGISTRATION[0]['VIN']
               previous_primary_owners(driver, vin)
               logger.info('Successfully queried history.')
       except Exception as e:
           logger.exception('Unable to query history to find previous owners.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from datetime import datetime, timedelta
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import print_result, get_document_ids, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def format_date_time(date_time):
       """
       Format the given date time to a string.
   
       :type date_time: :py:class:`datetime.datetime`
       :param date_time: The date time to format.
   
       :rtype: str
       :return: The formatted date time.
       """
       return date_time.strftime('`%Y-%m-%dT%H:%M:%S.%fZ`')
   
   
   def previous_primary_owners(transaction_executor, vin):
       """
       Find previous primary owners for the given VIN in a single transaction.
       In this example, query the `VehicleRegistration` history table to find all previous primary owners for a VIN.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type vin: str
       :param vin: VIN to find previous primary owners for.
       """
       person_ids = get_document_ids(transaction_executor, Constants.VEHICLE_REGISTRATION_TABLE_NAME, 'VIN', vin)
   
       todays_date = datetime.utcnow() - timedelta(seconds=1)
       three_months_ago = todays_date - timedelta(days=90)
       query = 'SELECT data.Owners.PrimaryOwner, metadata.version FROM history({}, {}, {}) AS h WHERE h.metadata.id = ?'.\
           format(Constants.VEHICLE_REGISTRATION_TABLE_NAME, format_date_time(three_months_ago),
                  format_date_time(todays_date))
   
       for ids in person_ids:
           logger.info("Querying the 'VehicleRegistration' table's history using VIN: {}.".format(vin))
           cursor = transaction_executor.execute_statement(query, ids)
           if not (print_result(cursor)) > 0:
               logger.info('No modification history found within the given time frame for document ID: {}'.format(ids))
   
   
   if __name__ == '__main__':
       """
       Query a table's history for a particular set of documents.
       """
       try:
           with create_qldb_session() as session:
               vin = SampleData.VEHICLE_REGISTRATION[0]['VIN']
               session.execute_lambda(lambda lambda_executor: previous_primary_owners(lambda_executor, vin),
                                      lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
               logger.info('Successfully queried history.')
       except Exception:
           logger.exception('Unable to query history to find previous owners.')
   ```

------
**참고**  
다음 구문에 내장된 [기록 함수](working.history.md#working.history.function)를 쿼리하여 문서의 개정 기록을 볼 수 있습니다  

     ```
     SELECT * FROM history( table_name [, `start-time` [, `end-time` ] ] ) AS h
     [ WHERE h.metadata.id = 'id' ]
     ```
*시작 시간*과 *종료 시간*은 모두 선택 사항입니다. 이 값은 백틱(``...``)으로 표시할 수 있는 Amazon Ion 리터럴 값입니다. 자세한 내용은 [Amazon QLDB에서 PartiQL을 사용한 Ion 쿼리](ql-reference.query.md) 섹션을 참조하세요.
가장 좋은 방법은 날짜 범위(*시작 시간* 및 *종료 시간*)와 문서 ID(`metadata.id`)를 모두 사용하여 기록 쿼리를 한정하는 것입니다. QLDB는 트랜잭션에서 `SELECT` 쿼리를 처리하며, 이 쿼리에는 [트랜잭션 시간 초과 제한](limits.md#limits.fixed)이 적용됩니다.  
QLDB 기록은 문서 ID로 인덱싱되며, 이번에는 추가 기록 인덱스를 만들 수 없습니다. 시작 시간과 종료 시간을 포함하는 기록 쿼리는 날짜 범위 한정이라는 이점을 갖습니다.

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python query_history.py
   ```

`vehicle-registration` 원장의 문서 개정을 암호화 방식으로 검증하려면 [7단계: 원장에 있는 문서 검증](getting-started.python.step-7.md)으로 진행하세요.

# 7단계: 원장에 있는 문서 검증
<a name="getting-started.python.step-7"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

Amazon QLDB를 사용하면 SHA-256 암호화 해싱을 사용하여 원장 저널에 있는 문서의 무결성을 효율적으로 검증할 수 있습니다. QLDB에서 검증 및 암호화 해싱이 작동하는 방식에 대한 자세한 내용은 [Amazon QLDB에서의 데이터 확인](verification.md)을 참조하세요.

이 단계에서는 `vehicle-registration` 원장의 `VehicleRegistration` 테이블에 있는 문서 개정을 검증합니다. 먼저 다이제스트를 요청합니다. 다이제스트는 출력 파일로 반환되며 원장의 전체 변경 내역에 대한 서명 역할을 합니다. 그런 다음 해당 다이제스트와 관련된 개정 증거를 요청합니다. 이 증거를 사용하면 모든 유효성 검사를 통과한 경우 개정 내용의 무결성을 확인할 수 있습니다.

**문서 개정을 검증하려면**

1. 검증에 필요한 QLDB 객체와 QLDB 응답 유형을 문자열로 변환하는 도우미 함수가 있는 유틸리티 모듈을 나타내는 다음 `.py` 파일을 검토하세요.

   1. `block_address.py`

      ```
      # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
      # SPDX-License-Identifier: MIT-0
      #
      # Permission is hereby granted, free of charge, to any person obtaining a copy of this
      # software and associated documentation files (the "Software"), to deal in the Software
      # without restriction, including without limitation the rights to use, copy, modify,
      # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
      # permit persons to whom the Software is furnished to do so.
      #
      # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
      # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
      # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
      # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
      # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
      # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      
      
      def block_address_to_dictionary(ion_dict):
          """
          Convert a block address from IonPyDict into a dictionary.
          Shape of the dictionary must be: {'IonText': "{strandId: <"strandId">, sequenceNo: <sequenceNo>}"}
      
          :type ion_dict: :py:class:`amazon.ion.simple_types.IonPyDict`/str
          :param ion_dict: The block address value to convert.
      
          :rtype: dict
          :return: The converted dict.
          """
          block_address = {'IonText': {}}
          if not isinstance(ion_dict, str):
              py_dict = '{{strandId: "{}", sequenceNo:{}}}'.format(ion_dict['strandId'], ion_dict['sequenceNo'])
              ion_dict = py_dict
          block_address['IonText'] = ion_dict
          return block_address
      ```

   1. `verifier.py`

      ```
      # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
      # SPDX-License-Identifier: MIT-0
      #
      # Permission is hereby granted, free of charge, to any person obtaining a copy of this
      # software and associated documentation files (the "Software"), to deal in the Software
      # without restriction, including without limitation the rights to use, copy, modify,
      # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
      # permit persons to whom the Software is furnished to do so.
      #
      # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
      # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
      # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
      # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
      # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
      # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      #
      # This code expects that you have AWS credentials setup per:
      # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
      from array import array
      from base64 import b64encode
      from functools import reduce
      from hashlib import sha256
      from random import randrange
      
      from amazon.ion.simpleion import loads
      
      HASH_LENGTH = 32
      UPPER_BOUND = 8
      
      
      def parse_proof(value_holder):
          """
          Parse the Proof object returned by QLDB into an iterator.
      
          The Proof object returned by QLDB is a dictionary like the following:
          {'IonText': '[{{<hash>}},{{<hash>}}]'}
      
          :type value_holder: dict
          :param value_holder: A structure containing an Ion string value.
      
          :rtype: :py:class:`amazon.ion.simple_types.IonPyList`
          :return: A list of hash values.
          """
          value_holder = value_holder.get('IonText')
          proof_list = loads(value_holder)
          return proof_list
      
      
      def parse_block(value_holder):
          """
          Parse the Block object returned by QLDB and retrieve block hash.
      
          :type value_holder: dict
          :param value_holder: A structure containing an Ion string value.
      
          :rtype: :py:class:`amazon.ion.simple_types.IonPyBytes`
          :return: The block hash.
          """
          value_holder = value_holder.get('IonText')
          block = loads(value_holder)
          block_hash = block.get('blockHash')
          return block_hash
      
      
      def flip_random_bit(original):
          """
          Flip a single random bit in the given hash value.
          This method is used to demonstrate QLDB's verification features.
      
          :type original: bytes
          :param original: The hash value to alter.
      
          :rtype: bytes
          :return: The altered hash with a single random bit changed.
          """
          assert len(original) != 0, 'Invalid bytes.'
      
          altered_position = randrange(len(original))
          bit_shift = randrange(UPPER_BOUND)
          altered_hash = bytearray(original).copy()
      
          altered_hash[altered_position] = altered_hash[altered_position] ^ (1 << bit_shift)
          return bytes(altered_hash)
      
      
      def compare_hash_values(hash1, hash2):
          """
          Compare two hash values by converting them into byte arrays, assuming they are little endian.
      
          :type hash1: bytes
          :param hash1: The hash value to compare.
      
          :type hash2: bytes
          :param hash2: The hash value to compare.
      
          :rtype: int
          :return: Zero if the hash values are equal, otherwise return the difference of the first pair of non-matching bytes.
          """
          assert len(hash1) == HASH_LENGTH
          assert len(hash2) == HASH_LENGTH
      
          hash_array1 = array('b', hash1)
          hash_array2 = array('b', hash2)
      
          for i in range(len(hash_array1) - 1, -1, -1):
              difference = hash_array1[i] - hash_array2[i]
              if difference != 0:
                  return difference
          return 0
      
      
      def join_hash_pairwise(hash1, hash2):
          """
          Take two hash values, sort them, concatenate them, and generate a new hash value from the concatenated values.
      
          :type hash1: bytes
          :param hash1: Hash value to concatenate.
      
          :type hash2: bytes
          :param hash2: Hash value to concatenate.
      
          :rtype: bytes
          :return: The new hash value generated from concatenated hash values.
          """
          if len(hash1) == 0:
              return hash2
          if len(hash2) == 0:
              return hash1
      
          concatenated = hash1 + hash2 if compare_hash_values(hash1, hash2) < 0 else hash2 + hash1
          new_hash_lib = sha256()
          new_hash_lib.update(concatenated)
          new_digest = new_hash_lib.digest()
          return new_digest
      
      
      def calculate_root_hash_from_internal_hashes(internal_hashes, leaf_hash):
          """
          Combine the internal hashes and the leaf hash until only one root hash remains.
      
          :type internal_hashes: map
          :param internal_hashes: An iterable over a list of hash values.
      
          :type leaf_hash: bytes
          :param leaf_hash: The revision hash to pair with the first hash in the Proof hashes list.
      
          :rtype: bytes
          :return: The root hash constructed by combining internal hashes.
          """
          root_hash = reduce(join_hash_pairwise, internal_hashes, leaf_hash)
          return root_hash
      
      
      def build_candidate_digest(proof, leaf_hash):
          """
          Build the candidate digest representing the entire ledger from the Proof hashes.
      
          :type proof: dict
          :param proof: The Proof object.
      
          :type leaf_hash: bytes
          :param leaf_hash: The revision hash to pair with the first hash in the Proof hashes list.
      
          :rtype: bytes
          :return: The calculated root hash.
          """
          parsed_proof = parse_proof(proof)
          root_hash = calculate_root_hash_from_internal_hashes(parsed_proof, leaf_hash)
          return root_hash
      
      
      def verify_document(document_hash, digest, proof):
          """
          Verify document revision against the provided digest.
      
          :type document_hash: bytes
          :param document_hash: The SHA-256 value representing the document revision to be verified.
      
          :type digest: bytes
          :param digest: The SHA-256 hash value representing the ledger digest.
      
          :type proof: dict
          :param proof: The Proof object retrieved from :func:`pyqldbsamples.get_revision.get_revision`.
      
          :rtype: bool
          :return: If the document revision verify against the ledger digest.
          """
          candidate_digest = build_candidate_digest(proof, document_hash)
          return digest == candidate_digest
      
      
      def to_base_64(input):
          """
          Encode input in base64.
      
          :type input: bytes
          :param input: Input to be encoded.
      
          :rtype: string
          :return: Return input that has been encoded in base64.
          """
          encoded_value = b64encode(input)
          return str(encoded_value, 'UTF-8')
      ```

   1. `qldb_string_utils.py`

      ```
      # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
      # SPDX-License-Identifier: MIT-0
      #
      # Permission is hereby granted, free of charge, to any person obtaining a copy of this
      # software and associated documentation files (the "Software"), to deal in the Software
      # without restriction, including without limitation the rights to use, copy, modify,
      # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
      # permit persons to whom the Software is furnished to do so.
      #
      # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
      # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
      # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
      # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
      # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
      # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      from amazon.ion.simpleion import dumps, loads
      
      
      def value_holder_to_string(value_holder):
          """
          Returns the string representation of a given `value_holder`.
      
          :type value_holder: dict
          :param value_holder: The `value_holder` to convert to string.
      
          :rtype: str
          :return: The string representation of the supplied `value_holder`.
          """
          ret_val = dumps(loads(value_holder), binary=False, indent='  ', omit_version_marker=True)
          val = '{{ IonText: {}}}'.format(ret_val)
          return val
      
      
      def block_response_to_string(block_response):
          """
          Returns the string representation of a given `block_response`.
      
          :type block_response: dict
          :param block_response: The `block_response` to convert to string.
      
          :rtype: str
          :return: The string representation of the supplied `block_response`.
          """
          string = ''
          if block_response.get('Block', {}).get('IonText') is not None:
              string += 'Block: ' + value_holder_to_string(block_response['Block']['IonText']) + ', '
      
          if block_response.get('Proof', {}).get('IonText') is not None:
              string += 'Proof: ' + value_holder_to_string(block_response['Proof']['IonText'])
      
          return '{' + string + '}'
      
      
      def digest_response_to_string(digest_response):
          """
          Returns the string representation of a given `digest_response`.
      
          :type digest_response: dict
          :param digest_response: The `digest_response` to convert to string.
      
          :rtype: str
          :return: The string representation of the supplied `digest_response`.
          """
          string = ''
          if digest_response.get('Digest') is not None:
              string += 'Digest: ' + str(digest_response['Digest']) + ', '
      
          if digest_response.get('DigestTipAddress', {}).get('IonText') is not None:
              string += 'DigestTipAddress: ' + value_holder_to_string(digest_response['DigestTipAddress']['IonText'])
      
          return '{' + string + '}'
      ```

1. 두 `.py` 프로그램(`get_digest.py` 및 `get_revision.py`)을 사용하여 다음 단계를 수행하세요.
   + `vehicle-registration` 원장에 새 다이제스트를 요청하세요.
   + `VehicleRegistration` 테이블에서 VIN `1N4AL11D75C109151`이 포함된 문서의 각 개정에 대한 증거를 요청합니다.
   + 반환된 다이제스트와 증거를 사용하여 다이제스트를 다시 계산하여 개정 내용을 검증합니다.

   `get_digest.py` 프로그램에는 다음 코드가 포함되어 있습니다.

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.qldb.qldb_string_utils import digest_response_to_string
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   
   def get_digest_result(name):
       """
       Get the digest of a ledger's journal.
   
       :type name: str
       :param name: Name of the ledger to operate on.
   
       :rtype: dict
       :return: The digest in a 256-bit hash value and a block address.
       """
       logger.info("Let's get the current digest of the ledger named {}".format(name))
       result = qldb_client.get_digest(Name=name)
       logger.info('Success. LedgerDigest: {}.'.format(digest_response_to_string(result)))
       return result
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       This is an example for retrieving the digest of a particular ledger.
       """
       try:
           get_digest_result(ledger_name)
       except Exception as e:
           logger.exception('Unable to get a ledger digest!')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```
**참고**  
`get_digest_result` 함수를 사용하여 원장에 있는 저널의 현재 *팁*을 포함하는 다이제스트를 요청합니다. 저널 팁은 QLDB가 요청을 수신한 시점을 기준으로 가장 최근에 커밋된 블록을 나타냅니다.

   `get_revision.py` 프로그램에는 다음 코드가 포함되어 있습니다.

------
#### [ 3.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from amazon.ion.simpleion import loads
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.get_digest import get_digest_result
   from pyqldbsamples.model.sample_data import SampleData, convert_object_to_ion
   from pyqldbsamples.qldb.block_address import block_address_to_dictionary
   from pyqldbsamples.verifier import verify_document, flip_random_bit, to_base_64
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   from pyqldbsamples.qldb.qldb_string_utils import value_holder_to_string
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   
   def get_revision(ledger_name, document_id, block_address, digest_tip_address):
       """
       Get the revision data object for a specified document ID and block address.
       Also returns a proof of the specified revision for verification.
   
       :type ledger_name: str
       :param ledger_name: Name of the ledger containing the document to query.
   
       :type document_id: str
       :param document_id: Unique ID for the document to be verified, contained in the committed view of the document.
   
       :type block_address: dict
       :param block_address: The location of the block to request.
   
       :type digest_tip_address: dict
       :param digest_tip_address: The latest block location covered by the digest.
   
       :rtype: dict
       :return: The response of the request.
       """
       result = qldb_client.get_revision(Name=ledger_name, BlockAddress=block_address, DocumentId=document_id,
                                         DigestTipAddress=digest_tip_address)
       return result
   
   
   def lookup_registration_for_vin(driver, vin):
       """
       Query revision history for a particular vehicle for verification.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type vin: str
       :param vin: VIN to query the revision history of a specific registration with.
   
       :rtype: :py:class:`pyqldb.cursor.buffered_cursor.BufferedCursor`
       :return: Cursor on the result set of the statement query.
       """
       logger.info("Querying the 'VehicleRegistration' table for VIN: {}...".format(vin))
       query = 'SELECT * FROM _ql_committed_VehicleRegistration WHERE data.VIN = ?'
       return driver.execute_lambda(lambda txn: txn.execute_statement(query, convert_object_to_ion(vin)))
   
   
   def verify_registration(driver, ledger_name, vin):
       """
       Verify each version of the registration for the given VIN.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type ledger_name: str
       :param ledger_name: The ledger to get digest from.
   
       :type vin: str
       :param vin: VIN to query the revision history of a specific registration with.
   
       :raises AssertionError: When verification failed.
       """
       logger.info("Let's verify the registration with VIN = {}, in ledger = {}.".format(vin, ledger_name))
       digest = get_digest_result(ledger_name)
       digest_bytes = digest.get('Digest')
       digest_tip_address = digest.get('DigestTipAddress')
   
       logger.info('Got a ledger digest: digest tip address = {}, digest = {}.'.format(
           value_holder_to_string(digest_tip_address.get('IonText')), to_base_64(digest_bytes)))
   
       logger.info('Querying the registration with VIN = {} to verify each version of the registration...'.format(vin))
       cursor = lookup_registration_for_vin(driver, vin)
       logger.info('Getting a proof for the document.')
   
       for row in cursor:
           block_address = row.get('blockAddress')
           document_id = row.get('metadata').get('id')
   
           result = get_revision(ledger_name, document_id, block_address_to_dictionary(block_address), digest_tip_address)
           revision = result.get('Revision').get('IonText')
           document_hash = loads(revision).get('hash')
   
           proof = result.get('Proof')
           logger.info('Got back a proof: {}.'.format(proof))
   
           verified = verify_document(document_hash, digest_bytes, proof)
           if not verified:
               raise AssertionError('Document revision is not verified.')
           else:
               logger.info('Success! The document is verified.')
   
           altered_document_hash = flip_random_bit(document_hash)
           logger.info("Flipping one bit in the document's hash and assert that the document is NOT verified. "
                       "The altered document hash is: {}.".format(to_base_64(altered_document_hash)))
           verified = verify_document(altered_document_hash, digest_bytes, proof)
           if verified:
               raise AssertionError('Expected altered document hash to not be verified against digest.')
           else:
               logger.info('Success! As expected flipping a bit in the document hash causes verification to fail.')
   
           logger.info('Finished verifying the registration with VIN = {} in ledger = {}.'.format(vin, ledger_name))
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Verify the integrity of a document revision in a QLDB ledger.
       """
       registration = SampleData.VEHICLE_REGISTRATION[0]
       vin = registration['VIN']
       try:
           with create_qldb_driver(ledger_name) as driver:
               verify_registration(driver, ledger_name, vin)
       except Exception as e:
           logger.exception('Unable to verify revision.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

------
#### [ 2.x ]

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from amazon.ion.simpleion import loads
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.get_digest import get_digest_result
   from pyqldbsamples.model.sample_data import SampleData, convert_object_to_ion
   from pyqldbsamples.qldb.block_address import block_address_to_dictionary
   from pyqldbsamples.verifier import verify_document, flip_random_bit, to_base_64
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   from pyqldbsamples.qldb.qldb_string_utils import value_holder_to_string
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   
   def get_revision(ledger_name, document_id, block_address, digest_tip_address):
       """
       Get the revision data object for a specified document ID and block address.
       Also returns a proof of the specified revision for verification.
   
       :type ledger_name: str
       :param ledger_name: Name of the ledger containing the document to query.
   
       :type document_id: str
       :param document_id: Unique ID for the document to be verified, contained in the committed view of the document.
   
       :type block_address: dict
       :param block_address: The location of the block to request.
   
       :type digest_tip_address: dict
       :param digest_tip_address: The latest block location covered by the digest.
   
       :rtype: dict
       :return: The response of the request.
       """
       result = qldb_client.get_revision(Name=ledger_name, BlockAddress=block_address, DocumentId=document_id,
                                         DigestTipAddress=digest_tip_address)
       return result
   
   
   def lookup_registration_for_vin(qldb_session, vin):
       """
       Query revision history for a particular vehicle for verification.
   
       :type qldb_session: :py:class:`pyqldb.session.qldb_session.QldbSession`
       :param qldb_session: An instance of the QldbSession class.
   
       :type vin: str
       :param vin: VIN to query the revision history of a specific registration with.
   
       :rtype: :py:class:`pyqldb.cursor.buffered_cursor.BufferedCursor`
       :return: Cursor on the result set of the statement query.
       """
       logger.info("Querying the 'VehicleRegistration' table for VIN: {}...".format(vin))
       query = 'SELECT * FROM _ql_committed_VehicleRegistration WHERE data.VIN = ?'
       parameters = [convert_object_to_ion(vin)]
       cursor = qldb_session.execute_statement(query, parameters)
       return cursor
   
   
   def verify_registration(qldb_session, ledger_name, vin):
       """
       Verify each version of the registration for the given VIN.
   
       :type qldb_session: :py:class:`pyqldb.session.qldb_session.QldbSession`
       :param qldb_session: An instance of the QldbSession class.
   
       :type ledger_name: str
       :param ledger_name: The ledger to get digest from.
   
       :type vin: str
       :param vin: VIN to query the revision history of a specific registration with.
   
       :raises AssertionError: When verification failed.
       """
       logger.info("Let's verify the registration with VIN = {}, in ledger = {}.".format(vin, ledger_name))
       digest = get_digest_result(ledger_name)
       digest_bytes = digest.get('Digest')
       digest_tip_address = digest.get('DigestTipAddress')
   
       logger.info('Got a ledger digest: digest tip address = {}, digest = {}.'.format(
           value_holder_to_string(digest_tip_address.get('IonText')), to_base_64(digest_bytes)))
   
       logger.info('Querying the registration with VIN = {} to verify each version of the registration...'.format(vin))
       cursor = lookup_registration_for_vin(qldb_session, vin)
       logger.info('Getting a proof for the document.')
   
       for row in cursor:
           block_address = row.get('blockAddress')
           document_id = row.get('metadata').get('id')
   
           result = get_revision(ledger_name, document_id, block_address_to_dictionary(block_address), digest_tip_address)
           revision = result.get('Revision').get('IonText')
           document_hash = loads(revision).get('hash')
   
           proof = result.get('Proof')
           logger.info('Got back a proof: {}.'.format(proof))
   
           verified = verify_document(document_hash, digest_bytes, proof)
           if not verified:
               raise AssertionError('Document revision is not verified.')
           else:
               logger.info('Success! The document is verified.')
   
           altered_document_hash = flip_random_bit(document_hash)
           logger.info("Flipping one bit in the document's hash and assert that the document is NOT verified. "
                       "The altered document hash is: {}.".format(to_base_64(altered_document_hash)))
           verified = verify_document(altered_document_hash, digest_bytes, proof)
           if verified:
               raise AssertionError('Expected altered document hash to not be verified against digest.')
           else:
               logger.info('Success! As expected flipping a bit in the document hash causes verification to fail.')
   
           logger.info('Finished verifying the registration with VIN = {} in ledger = {}.'.format(vin, ledger_name))
   
   
   if __name__ == '__main__':
       """
       Verify the integrity of a document revision in a QLDB ledger.
       """
       registration = SampleData.VEHICLE_REGISTRATION[0]
       vin = registration['VIN']
       try:
           with create_qldb_session() as session:
               verify_registration(session, Constants.LEDGER_NAME, vin)
       except Exception:
           logger.exception('Unable to verify revision.')
   ```

------
**참고**  
`get_revision` 함수가 지정된 문서 개정에 대한 증거를 반환하면 이 프로그램은 클라이언트 측 API를 사용하여 해당 개정본을 확인합니다.

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python get_revision.py
   ```

`vehicle-registration` 원장을 더 이상 사용할 필요가 없는 경우 [8단계(선택 사항): 리소스 정리](getting-started.python.step-8.md)로 진행하세요.

# 8단계(선택 사항): 리소스 정리
<a name="getting-started.python.step-8"></a>

**중요**  
지원 종료 알림: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

`vehicle-registration` 원장을 계속 사용할 수 있습니다. 그러나 더 이상 필요하지 않은 경우 삭제해야 합니다.

**원장을 삭제하려면**

1. 다음 프로그램(`delete_ledger.py`)을 사용하여 `vehicle-registration` 원장과 모든 내용을 삭제하세요.

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   from time import sleep
   
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.describe_ledger import describe_ledger
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   LEDGER_DELETION_POLL_PERIOD_SEC = 20
   
   
   def delete_ledger(ledger_name):
       """
       Send a request to QLDB to delete the specified ledger.
   
       :type ledger_name: str
       :param ledger_name: Name for the ledger to be deleted.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info('Attempting to delete the ledger with name: {}...'.format(ledger_name))
       result = qldb_client.delete_ledger(Name=ledger_name)
       logger.info('Success.')
       return result
   
   
   def wait_for_deleted(ledger_name):
       """
       Wait for the ledger to be deleted.
   
       :type ledger_name: str
       :param ledger_name: The ledger to check on.
       """
       logger.info('Waiting for the ledger to be deleted...')
       while True:
           try:
               describe_ledger(ledger_name)
               logger.info('The ledger is still being deleted. Please wait...')
               sleep(LEDGER_DELETION_POLL_PERIOD_SEC)
           except qldb_client.exceptions.ResourceNotFoundException:
               logger.info('Success. The ledger is deleted.')
               break
   
   
   def set_deletion_protection(ledger_name, deletion_protection):
       """
       Update an existing ledger's deletion protection.
   
       :type ledger_name: str
       :param ledger_name: Name of the ledger to update.
   
       :type deletion_protection: bool
       :param deletion_protection: Enable or disable the deletion protection.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info("Let's set deletion protection to {} for the ledger with name {}.".format(deletion_protection,
                                                                                             ledger_name))
       result = qldb_client.update_ledger(Name=ledger_name, DeletionProtection=deletion_protection)
       logger.info('Success. Ledger updated: {}'.format(result))
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Delete a ledger.
       """
       try:
           set_deletion_protection(ledger_name, False)
           delete_ledger(ledger_name)
           wait_for_deleted(ledger_name)
       except Exception as e:
           logger.exception('Unable to delete the ledger.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```
**참고**  
원장에 대해 삭제 방지가 활성화된 경우 QLDB API를 사용하여 원장을 삭제하기 전에 먼저 이를 비활성화해야 합니다.

   또한 `delete_ledger.py` 파일은 다음 프로그램(`describe_ledger.py`)에 대한 종속성을 갖습니다.

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   
   def describe_ledger(ledger_name):
       """
       Describe a ledger.
   
       :type ledger_name: str
       :param ledger_name: Name of the ledger to describe.
       """
       logger.info('describe ledger with name: {}.'.format(ledger_name))
       result = qldb_client.describe_ledger(Name=ledger_name)
       result.pop('ResponseMetadata')
       logger.info('Success. Ledger description: {}.'.format(result))
       return result
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Describe a QLDB ledger.
       """
       try:
           describe_ledger(ledger_name)
       except Exception as e:
           logger.exception('Unable to describe a ledger.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

1. 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   python delete_ledger.py
   ```