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# Pesan lokal publikasi/berlangganan
<a name="ipc-publish-subscribe"></a>

Olah pesan publikasi/berlangganan (pubsub) memungkinkan Anda untuk mengirim dan menerima pesan ke topik. Komponen dapat mempublikasikan pesan pada topik untuk mengirim pesan ke komponen lain. Kemudian, komponen yang berlangganan topik itu dapat bertindak atas pesan yang diterimanya.

**catatan**  
Anda tidak dapat menggunakan layanan publish/subscribe IPC ini untuk mempublikasikan atau berlangganan AWS IoT Core MQTT. Untuk informasi selengkapnya tentang cara bertukar pesan dengan AWS IoT Core MQTT, lihat. [Terbitkan/berlangganan pesan MQTT AWS IoT Core](ipc-iot-core-mqtt.md)

**Topics**
+ [SDK (Versi Minimum)](#ipc-publish-subscribe-sdk-versions)
+ [Otorisasi](#ipc-publish-subscribe-authorization)
+ [PublishToTopic](#ipc-operation-publishtotopic)
+ [SubscribeToTopic](#ipc-operation-subscribetotopic)
+ [Contoh](#ipc-publish-subscribe-examples)

## SDK (Versi Minimum)
<a name="ipc-publish-subscribe-sdk-versions"></a>

Tabel berikut mencantumkan versi minimum SDKs yang dapat Anda gunakan untuk mempublikasikan dan berlangganan pesan ke dan dari topik lokal.


| SDK | Versi minimum | 
| --- | --- | 
|  [AWS IoT Greengrass Komponen SDK (C, C \$1\$1, Karat)](https://github.com/aws-greengrass/aws-greengrass-component-sdk)  |  v1.0.0  | 
|  [AWS IoT Device SDK untuk Java v2](https://github.com/aws/aws-iot-device-sdk-java-v2)  |  v1.2.10  | 
|  [AWS IoT Device SDK untuk Python v2](https://github.com/aws/aws-iot-device-sdk-python-v2)  |  v1.5.3  | 
|  [AWS IoT Device SDK untuk C\$1\$1 v2](https://github.com/aws/aws-iot-device-sdk-cpp-v2)  |  v1.17.0  | 
|  [AWS IoT Device SDK for JavaScript v2](https://github.com/aws/aws-iot-device-sdk-js-v2)  |  v1.12.0  | 

## Otorisasi
<a name="ipc-publish-subscribe-authorization"></a>

Untuk menggunakan publish/subscribe pesan lokal dalam komponen kustom, Anda harus menentukan kebijakan otorisasi yang memungkinkan komponen Anda mengirim dan menerima pesan ke topik. Untuk informasi tentang cara menentukan kebijakan otorisasi, lihat [Otorisasi komponen untuk melakukan operasi IPC](interprocess-communication.md#ipc-authorization-policies).

Kebijakan otorisasi untuk publish/subscribe pengiriman pesan memiliki properti berikut.

**Pengenal layanan IPC:** `aws.greengrass.ipc.pubsub`


| Operasi | Deskripsi | Sumber daya | 
| --- | --- | --- | 
|  `aws.greengrass#PublishToTopic`  |  Memungkinkan komponen untuk mempublikasikan pesan ke topik MQTT yang Anda tentukan.  |  String topik, seperti`test/topic`. Gunakan `*` untuk mencocokkan kombinasi karakter apa pun dalam suatu topik. String topik ini mendukung wildcard topik MQTT (`#` dan `+`).  | 
|  `aws.greengrass#SubscribeToTopic`  |  Memungkinkan komponen untuk berlangganan pesan untuk topik yang Anda tentukan.  |  String topik, seperti`test/topic`. Gunakan `*` untuk mencocokkan kombinasi karakter apa pun dalam suatu topik. <a name="ipc-local-publish-subscribe-authorization-mqtt-wildcards"></a>Di [Greengrass](greengrass-nucleus-component.md) nucleus v2.6.0 dan yang lebih baru, Anda dapat berlangganan topik yang berisi wildcard topik MQTT (dan). `#` `+` String topik ini mendukung wildcard topik MQTT sebagai karakter literal. Misalnya, jika kebijakan otorisasi komponen memberikan akses ke`test/topic/#`, komponen dapat berlangganan`test/topic/#`, tetapi tidak dapat berlangganan. `test/topic/filter`  | 
|  `*`  |  Memungkinkan komponen untuk mempublikasikan dan berlanggan pesan untuk topik yang Anda tentukan.  |  String topik, seperti`test/topic`. Gunakan `*` untuk mencocokkan kombinasi karakter apa pun dalam suatu topik. <a name="ipc-local-publish-subscribe-authorization-mqtt-wildcards"></a>Di [Greengrass](greengrass-nucleus-component.md) nucleus v2.6.0 dan yang lebih baru, Anda dapat berlangganan topik yang berisi wildcard topik MQTT (dan). `#` `+` String topik ini mendukung wildcard topik MQTT sebagai karakter literal. Misalnya, jika kebijakan otorisasi komponen memberikan akses ke`test/topic/#`, komponen dapat berlangganan`test/topic/#`, tetapi tidak dapat berlangganan. `test/topic/filter`  | 

### Contoh kebijakan otorisasi
<a name="ipc-publish-subscribe-authorization-policy-examples"></a>

Anda dapat mereferensikan contoh kebijakan otorisasi berikut untuk membantu Anda mengonfigurasi kebijakan otorisasi untuk komponen Anda.

**Example Contoh kebijakan otorisasi**  
Kebijakan otorisasi contoh berikut ini memungkinkan komponen untuk mempublikasikan dan berlangganan semua topik.  

```
{
  "accessControl": {
    "aws.greengrass.ipc.pubsub": {
      "com.example.MyLocalPubSubComponent:pubsub:1": {
        "policyDescription": "Allows access to publish/subscribe to all topics.",
        "operations": [
          "aws.greengrass#PublishToTopic",
          "aws.greengrass#SubscribeToTopic"
        ],
        "resources": [
          "*"
        ]
      }
    }
  }
}
```

## PublishToTopic
<a name="ipc-operation-publishtotopic"></a>

Publikasikan pesan ke topik.

### Permintaan
<a name="ipc-operation-publishtotopic-request"></a>

Permintaan operasi ini memiliki parameter berikut:

`topic`  
Topik yang pesannya dipublikasikan.

`publishMessage`(Python:) `publish_message`  
Pesan yang akan dipublikasikan. Objek ini, `PublishMessage`, berisi informasi berikut. Anda harus menentukan salah satu dari `jsonMessage` dan `binaryMessage`.  <a name="ipc-publish-subscribe-message-shape"></a>  
`jsonMessage`(Python:) `json_message`  
(Opsional) Sebuah pesan JSON. Objek ini, `JsonMessage`, berisi informasi berikut:    
`message`  
Pesan JSON sebagai objek.  
`context`  <a name="ipc-publish-subscribe-message-context-variable"></a>
Konteks pesan, seperti topik di mana pesan itu diterbitkan.  
[Fitur ini tersedia untuk v2.6.0 dan yang lebih baru dari komponen inti Greengrass.](greengrass-nucleus-component.md) Tabel berikut mencantumkan versi minimum AWS IoT Device SDK yang harus Anda gunakan untuk mengakses konteks pesan.      
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/id_id/greengrass/v2/developerguide/ipc-publish-subscribe.html)
Perangkat lunak AWS IoT Greengrass Core menggunakan objek pesan yang sama dalam `PublishToTopic` dan `SubscribeToTopic` operasi. Perangkat lunak AWS IoT Greengrass Core menetapkan objek konteks ini dalam pesan saat Anda berlangganan, dan mengabaikan objek konteks ini dalam pesan yang Anda terbitkan.
Objek ini, `MessageContext`, berisi informasi berikut:    
`topic`  
Topik di mana pesan itu diterbitkan.  
`binaryMessage`(Python:) `binary_message`  
(Opsional) Sebuah pesan biner. Objek ini, `BinaryMessage`, berisi informasi berikut:    
`message`  
Pesan biner sebagai gumpalan.  
`context`  <a name="ipc-publish-subscribe-message-context-variable"></a>
Konteks pesan, seperti topik di mana pesan itu diterbitkan.  
[Fitur ini tersedia untuk v2.6.0 dan yang lebih baru dari komponen inti Greengrass.](greengrass-nucleus-component.md) Tabel berikut mencantumkan versi minimum AWS IoT Device SDK yang harus Anda gunakan untuk mengakses konteks pesan.      
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/id_id/greengrass/v2/developerguide/ipc-publish-subscribe.html)
Perangkat lunak AWS IoT Greengrass Core menggunakan objek pesan yang sama dalam `PublishToTopic` dan `SubscribeToTopic` operasi. Perangkat lunak AWS IoT Greengrass Core menetapkan objek konteks ini dalam pesan saat Anda berlangganan, dan mengabaikan objek konteks ini dalam pesan yang Anda terbitkan.
Objek ini, `MessageContext`, berisi informasi berikut:    
`topic`  
Topik di mana pesan itu diterbitkan.

### Respons
<a name="ipc-operation-publishtotopic-response"></a>

Operasi ini tidak memberikan informasi apa pun dalam tanggapannya.

### Contoh
<a name="ipc-operation-publishtotopic-examples"></a>

Contoh-contoh berikut ini menunjukkan cara memanggil operasi ini dalam kode komponen kustom.

------
#### [ Java (IPC client V2) ]

**Example Contoh: Publikasikan pesan biner**  

```
package com.aws.greengrass.docs.samples.ipc;

import software.amazon.awssdk.aws.greengrass.GreengrassCoreIPCClientV2;
import software.amazon.awssdk.aws.greengrass.model.BinaryMessage;
import software.amazon.awssdk.aws.greengrass.model.PublishMessage;
import software.amazon.awssdk.aws.greengrass.model.PublishToTopicRequest;
import software.amazon.awssdk.aws.greengrass.model.PublishToTopicResponse;
import software.amazon.awssdk.aws.greengrass.model.UnauthorizedError;

import java.nio.charset.StandardCharsets;

public class PublishToTopicV2 {

    public static void main(String[] args) {
        String topic = args[0];
        String message = args[1];
        try (GreengrassCoreIPCClientV2 ipcClient = GreengrassCoreIPCClientV2.builder().build()) {
            PublishToTopicV2.publishBinaryMessageToTopic(ipcClient, topic, message);
            System.out.println("Successfully published to topic: " + topic);
        } catch (Exception e) {
            if (e.getCause() instanceof UnauthorizedError) {
                System.err.println("Unauthorized error while publishing to topic: " + topic);
            } else {
                System.err.println("Exception occurred when using IPC.");
            }
            e.printStackTrace();
            System.exit(1);
        }
    }

    public static PublishToTopicResponse publishBinaryMessageToTopic(
            GreengrassCoreIPCClientV2 ipcClient, String topic, String message) throws InterruptedException {
        BinaryMessage binaryMessage =
                new BinaryMessage().withMessage(message.getBytes(StandardCharsets.UTF_8));
        PublishMessage publishMessage = new PublishMessage().withBinaryMessage(binaryMessage);
        PublishToTopicRequest publishToTopicRequest =
                new PublishToTopicRequest().withTopic(topic).withPublishMessage(publishMessage);
        return ipcClient.publishToTopic(publishToTopicRequest);
    }
}
```

------
#### [ Python (IPC client V2) ]

**Example Contoh: Publikasikan pesan biner**  

```
import sys
import traceback

from awsiot.greengrasscoreipc.clientv2 import GreengrassCoreIPCClientV2
from awsiot.greengrasscoreipc.model import (
    PublishMessage,
    BinaryMessage
)


def main():
    args = sys.argv[1:]
    topic = args[0]
    message = args[1]

    try:
        ipc_client = GreengrassCoreIPCClientV2()
        publish_binary_message_to_topic(ipc_client, topic, message)
        print('Successfully published to topic: ' + topic)
    except Exception:
        print('Exception occurred', file=sys.stderr)
        traceback.print_exc()
        exit(1)


def publish_binary_message_to_topic(ipc_client, topic, message):
    binary_message = BinaryMessage(message=bytes(message, 'utf-8'))
    publish_message = PublishMessage(binary_message=binary_message)
    return ipc_client.publish_to_topic(topic=topic, publish_message=publish_message)


if __name__ == '__main__':
    main()
```

------
#### [ C\$1\$1 (IPC client V1) ]

**Example Contoh: Publikasikan pesan biner**  

```
#include <iostream>

#include <aws/crt/Api.h>
#include <aws/greengrass/GreengrassCoreIpcClient.h>

using namespace Aws::Crt;
using namespace Aws::Greengrass;

class IpcClientLifecycleHandler : public ConnectionLifecycleHandler {
    void OnConnectCallback() override {
        // Handle connection to IPC service.
    }

    void OnDisconnectCallback(RpcError error) override {
        // Handle disconnection from IPC service.
    }

    bool OnErrorCallback(RpcError error) override {
        // Handle IPC service connection error.
        return true;
    }
};

int main() {
    ApiHandle apiHandle(g_allocator);
    Io::EventLoopGroup eventLoopGroup(1);
    Io::DefaultHostResolver socketResolver(eventLoopGroup, 64, 30);
    Io::ClientBootstrap bootstrap(eventLoopGroup, socketResolver);
    IpcClientLifecycleHandler ipcLifecycleHandler;
    GreengrassCoreIpcClient ipcClient(bootstrap);
    auto connectionStatus = ipcClient.Connect(ipcLifecycleHandler).get();
    if (!connectionStatus) {
        std::cerr << "Failed to establish IPC connection: " << connectionStatus.StatusToString() << std::endl;
        exit(-1);
    }

    String topic("my/topic");
    String message("Hello, World!");
    int timeout = 10;

    PublishToTopicRequest request;
    Vector<uint8_t> messageData({message.begin(), message.end()});
    BinaryMessage binaryMessage;
    binaryMessage.SetMessage(messageData);
    PublishMessage publishMessage;
    publishMessage.SetBinaryMessage(binaryMessage);
    request.SetTopic(topic);
    request.SetPublishMessage(publishMessage);

    auto operation = ipcClient.NewPublishToTopic();
    auto activate = operation->Activate(request, nullptr);
    activate.wait();

    auto responseFuture = operation->GetResult();
    if (responseFuture.wait_for(std::chrono::seconds(timeout)) == std::future_status::timeout) {
        std::cerr << "Operation timed out while waiting for response from Greengrass Core." << std::endl;
        exit(-1);
    }

    auto response = responseFuture.get();
    if (!response) {
        // Handle error.
        auto errorType = response.GetResultType();
        if (errorType == OPERATION_ERROR) {
            auto *error = response.GetOperationError();
            (void)error;
            // Handle operation error.
        } else {
            // Handle RPC error.
        }
    }
    return 0;
}
```

------
#### [ JavaScript ]

**Example Contoh: Publikasikan pesan biner**  

```
    
import * as greengrasscoreipc from "aws-iot-device-sdk-v2/dist/greengrasscoreipc";
import {BinaryMessage, PublishMessage, PublishToTopicRequest} from "aws-iot-device-sdk-v2/dist/greengrasscoreipc/model";
 
class PublishToTopic {
    private ipcClient : greengrasscoreipc.Client
    private readonly topic : string;
    private readonly messageString : string;
 
    constructor() {
        // define your own constructor, e.g.
        this.topic = "<define_your_topic>";
        this.messageString = "<define_your_message_string>";
        this.publishToTopic().then(r => console.log("Started workflow"));
    }
 
    private async publishToTopic() {
        try {
            this.ipcClient = await getIpcClient();
 
            const binaryMessage : BinaryMessage = {
                message: this.messageString
            }
 
            const publishMessage : PublishMessage = {
                binaryMessage: binaryMessage
            }
 
            const request : PublishToTopicRequest = {
                topic: this.topic,
                publishMessage: publishMessage
            }
 
            this.ipcClient.publishToTopic(request).finally(() => console.log(`Published message ${publishMessage.binaryMessage?.message} to topic`))
 
        } catch (e) {
            // parse the error depending on your use cases
            throw e
        }
    }
}
 
 
export async function getIpcClient(){
    try {
        const ipcClient = greengrasscoreipc.createClient();
        await ipcClient.connect()
            .catch(error => {
                // parse the error depending on your use cases
                throw error;
            });
        return ipcClient
    } catch (err) {
        // parse the error depending on your use cases
        throw err
    }
}
 
// starting point
const publishToTopic = new PublishToTopic();
```

------
#### [ Rust ]

**Example Contoh: Publikasikan pesan biner**  

```
use gg_sdk::Sdk;

fn main() {
    let sdk = Sdk::init();
    sdk.connect().expect("Failed to establish IPC connection");

    let message = b"Hello, World";
    let topic = "my/topic";

    sdk.publish_to_topic_binary(topic, message)
        .expect("Failed to publish to topic");

    println!("Successfully published to topic: {topic}");
}
```

------
#### [ C ]

**Example Contoh: Publikasikan pesan biner**  

```
#include <gg/error.h>
#include <gg/ipc/client.h>
#include <gg/sdk.h>
#include <stdio.h>
#include <stdlib.h>

int main(void) {
    gg_sdk_init();

    GgError err = ggipc_connect();
    if (err != GG_ERR_OK) {
        fprintf(stderr, "Failed to establish IPC connection.\n");
        exit(-1);
    }

    GgBuffer message = GG_STR("Hello, World");
    GgBuffer topic = GG_STR("my/topic");

    err = ggipc_publish_to_topic_binary(topic, message);
    if (err != GG_ERR_OK) {
        fprintf(
            stderr,
            "Failed to publish to topic: %.*s\n",
            (int) topic.len,
            topic.data
        );
        exit(-1);
    }

    printf(
        "Successfully published to topic: %.*s\n", (int) topic.len, topic.data
    );
}
```

------
#### [ C\$1\$1 (Component SDK) ]

**Example Contoh: Publikasikan pesan biner**  

```
#include <gg/ipc/client.hpp>
#include <iostream>

int main() {
    auto &client = gg::ipc::Client::get();

    auto error = client.connect();
    if (error) {
        std::cerr << "Failed to establish IPC connection.\n";
        exit(-1);
    }

    std::string_view message = "Hello, World";
    std::string_view topic = "my/topic";

    error = client.publish_to_topic(topic, message);
    if (error) {
        std::cerr << "Failed to publish to topic: " << topic << "\n";
        exit(-1);
    }

    std::cout << "Successfully published to topic: " << topic << "\n";
}
```

------

## SubscribeToTopic
<a name="ipc-operation-subscribetotopic"></a>

Berlangganan pesan tentang suatu topik.

<a name="ipc-subscribe-operation-note"></a>Operasi ini adalah operasi berlangganan di mana Anda berlangganan aliran pesan peristiwa. Untuk menggunakan operasi ini, tentukan bagian yang menangani respons aliran dengan fungsi yang menangani pesan peristiwa, kesalahan, dan penutupan aliran. Untuk informasi selengkapnya, lihat [Berlangganan pengaliran peristiwa IPC](interprocess-communication.md#ipc-subscribe-operations).

**Jenis pesan peristiwa:** `SubscriptionResponseMessage`

### Permintaan
<a name="ipc-operation-subscribetotopic-request"></a>

Permintaan operasi ini memiliki parameter berikut:

`topic`  
Topik yang harus dijadikan langganan.  
Di [Greengrass](greengrass-nucleus-component.md) nucleus v2.6.0 dan yang lebih baru, topik ini mendukung wildcard topik MQTT (dan). `#` `+`

`receiveMode`(Python:) `receive_mode`  
(Opsional) Perilaku yang menentukan apakah komponen menerima pesan dari dirinya sendiri. Anda dapat mengubah perilaku ini agar komponen dapat bertindak berdasarkan pesannya sendiri. Perilaku default tergantung pada apakah topik berisi wildcard MQTT. Pilih dari salah satu pilihan berikut:  
+ `RECEIVE_ALL_MESSAGES`— Menerima semua pesan yang cocok dengan topik, termasuk pesan dari komponen yang berlangganan.

  Mode ini adalah opsi default saat Anda berlangganan topik yang tidak berisi wildcard MQTT.
+ `RECEIVE_MESSAGES_FROM_OTHERS`— Menerima semua pesan yang cocok dengan topik, kecuali pesan dari komponen yang berlangganan.

  Mode ini adalah opsi default saat Anda berlangganan topik yang berisi wildcard MQTT.
[Fitur ini tersedia untuk v2.6.0 dan yang lebih baru dari komponen inti Greengrass.](greengrass-nucleus-component.md) Tabel berikut mencantumkan versi minimum AWS IoT Device SDK yang harus Anda gunakan untuk mengatur mode terima.      
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/id_id/greengrass/v2/developerguide/ipc-publish-subscribe.html)

### Respons
<a name="ipc-operation-subscribetotopic-response"></a>

Tanggapan operasi ini memiliki informasi berikut:

`messages`  
Aliran pesan. Objek ini, `SubscriptionResponseMessage`, berisi informasi berikut. Setiap pesan berisi `jsonMessage` atau `binaryMessage`.  <a name="ipc-publish-subscribe-message-shape"></a>  
`jsonMessage`(Python:) `json_message`  
(Opsional) Sebuah pesan JSON. Objek ini, `JsonMessage`, berisi informasi berikut:    
`message`  
Pesan JSON sebagai objek.  
`context`  <a name="ipc-publish-subscribe-message-context-variable"></a>
Konteks pesan, seperti topik di mana pesan itu diterbitkan.  
[Fitur ini tersedia untuk v2.6.0 dan yang lebih baru dari komponen inti Greengrass.](greengrass-nucleus-component.md) Tabel berikut mencantumkan versi minimum AWS IoT Device SDK yang harus Anda gunakan untuk mengakses konteks pesan.      
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/id_id/greengrass/v2/developerguide/ipc-publish-subscribe.html)
Perangkat lunak AWS IoT Greengrass Core menggunakan objek pesan yang sama dalam `PublishToTopic` dan `SubscribeToTopic` operasi. Perangkat lunak AWS IoT Greengrass Core menetapkan objek konteks ini dalam pesan saat Anda berlangganan, dan mengabaikan objek konteks ini dalam pesan yang Anda terbitkan.
Objek ini, `MessageContext`, berisi informasi berikut:    
`topic`  
Topik di mana pesan itu diterbitkan.  
`binaryMessage`(Python:) `binary_message`  
(Opsional) Sebuah pesan biner. Objek ini, `BinaryMessage`, berisi informasi berikut:    
`message`  
Pesan biner sebagai gumpalan.  
`context`  <a name="ipc-publish-subscribe-message-context-variable"></a>
Konteks pesan, seperti topik di mana pesan itu diterbitkan.  
[Fitur ini tersedia untuk v2.6.0 dan yang lebih baru dari komponen inti Greengrass.](greengrass-nucleus-component.md) Tabel berikut mencantumkan versi minimum AWS IoT Device SDK yang harus Anda gunakan untuk mengakses konteks pesan.      
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/id_id/greengrass/v2/developerguide/ipc-publish-subscribe.html)
Perangkat lunak AWS IoT Greengrass Core menggunakan objek pesan yang sama dalam `PublishToTopic` dan `SubscribeToTopic` operasi. Perangkat lunak AWS IoT Greengrass Core menetapkan objek konteks ini dalam pesan saat Anda berlangganan, dan mengabaikan objek konteks ini dalam pesan yang Anda terbitkan.
Objek ini, `MessageContext`, berisi informasi berikut:    
`topic`  
Topik di mana pesan itu diterbitkan.

`topicName`(Python:) `topic_name`  
Topik yang pesannya dipublikasikan.  
Properti ini saat ini tidak digunakan. Di [Greengrass](greengrass-nucleus-component.md) nucleus v2.6.0 dan yang lebih baru, Anda bisa mendapatkan nilai dari `SubscriptionResponseMessage` a untuk mendapatkan topik `(jsonMessage|binaryMessage).context.topic` di mana pesan itu diterbitkan.

### Contoh
<a name="ipc-operation-subscribetotopic-examples"></a>

Contoh-contoh berikut ini menunjukkan cara memanggil operasi ini dalam kode komponen kustom.

------
#### [ Java (IPC client V2) ]

**Example Contoh: Berlangganan publish/subscribe pesan lokal**  <a name="ipc-operation-subscribetotopic-example-java-v2"></a>

```
package com.aws.greengrass.docs.samples.ipc;

import software.amazon.awssdk.aws.greengrass.GreengrassCoreIPCClientV2;
import software.amazon.awssdk.aws.greengrass.SubscribeToTopicResponseHandler;
import software.amazon.awssdk.aws.greengrass.model.*;

import java.nio.charset.StandardCharsets;
import java.util.Optional;

public class SubscribeToTopicV2 {

    public static void main(String[] args) {
        String topic = args[0];
        try (GreengrassCoreIPCClientV2 ipcClient = GreengrassCoreIPCClientV2.builder().build()) {
            SubscribeToTopicRequest request = new SubscribeToTopicRequest().withTopic(topic);
            GreengrassCoreIPCClientV2.StreamingResponse<SubscribeToTopicResponse,
                    SubscribeToTopicResponseHandler> response =
                    ipcClient.subscribeToTopic(request, SubscribeToTopicV2::onStreamEvent,
                            Optional.of(SubscribeToTopicV2::onStreamError),
                            Optional.of(SubscribeToTopicV2::onStreamClosed));
            SubscribeToTopicResponseHandler responseHandler = response.getHandler();
            System.out.println("Successfully subscribed to topic: " + topic);

            // Keep the main thread alive, or the process will exit.
            try {
                while (true) {
                    Thread.sleep(10000);
                }
            } catch (InterruptedException e) {
                System.out.println("Subscribe interrupted.");
            }

            // To stop subscribing, close the stream.
            responseHandler.closeStream();
        } catch (Exception e) {
            if (e.getCause() instanceof UnauthorizedError) {
                System.err.println("Unauthorized error while publishing to topic: " + topic);
            } else {
                System.err.println("Exception occurred when using IPC.");
            }
            e.printStackTrace();
            System.exit(1);
        }
    }

    public static void onStreamEvent(SubscriptionResponseMessage subscriptionResponseMessage) {
        try {
            BinaryMessage binaryMessage = subscriptionResponseMessage.getBinaryMessage();
            String message = new String(binaryMessage.getMessage(), StandardCharsets.UTF_8);
            String topic = binaryMessage.getContext().getTopic();
            System.out.printf("Received new message on topic %s: %s%n", topic, message);
        } catch (Exception e) {
            System.err.println("Exception occurred while processing subscription response " +
                    "message.");
            e.printStackTrace();
        }
    }

    public static boolean onStreamError(Throwable error) {
        System.err.println("Received a stream error.");
        error.printStackTrace();
        return false; // Return true to close stream, false to keep stream open.
    }

    public static void onStreamClosed() {
        System.out.println("Subscribe to topic stream closed.");
    }
}
```

------
#### [ Python (IPC client V2) ]

**Example Contoh: Berlangganan publish/subscribe pesan lokal**  <a name="ipc-operation-subscribetotopic-example-python-v2"></a>

```
import sys
import time
import traceback

from awsiot.greengrasscoreipc.clientv2 import GreengrassCoreIPCClientV2
from awsiot.greengrasscoreipc.model import (
    SubscriptionResponseMessage,
    UnauthorizedError
)


def main():
    args = sys.argv[1:]
    topic = args[0]

    try:
        ipc_client = GreengrassCoreIPCClientV2()
        # Subscription operations return a tuple with the response and the operation.
        _, operation = ipc_client.subscribe_to_topic(topic=topic, on_stream_event=on_stream_event,
                                                     on_stream_error=on_stream_error, on_stream_closed=on_stream_closed)
        print('Successfully subscribed to topic: ' + topic)

        # Keep the main thread alive, or the process will exit.
        try:
            while True:
                time.sleep(10)
        except InterruptedError:
            print('Subscribe interrupted.')

        # To stop subscribing, close the stream.
        operation.close()
    except UnauthorizedError:
        print('Unauthorized error while subscribing to topic: ' +
              topic, file=sys.stderr)
        traceback.print_exc()
        exit(1)
    except Exception:
        print('Exception occurred', file=sys.stderr)
        traceback.print_exc()
        exit(1)


def on_stream_event(event: SubscriptionResponseMessage) -> None:
    try:
        message = str(event.binary_message.message, 'utf-8')
        topic = event.binary_message.context.topic
        print('Received new message on topic %s: %s' % (topic, message))
    except:
        traceback.print_exc()


def on_stream_error(error: Exception) -> bool:
    print('Received a stream error.', file=sys.stderr)
    traceback.print_exc()
    return False  # Return True to close stream, False to keep stream open.


def on_stream_closed() -> None:
    print('Subscribe to topic stream closed.')


if __name__ == '__main__':
    main()
```

------
#### [ C\$1\$1 (IPC client V1) ]

**Example Contoh: Berlangganan publish/subscribe pesan lokal**  <a name="ipc-operation-subscribetotopic-example-cpp"></a>

```
#include <iostream>

#include </crt/Api.h>
#include <aws/greengrass/GreengrassCoreIpcClient.h>

using namespace Aws::Crt;
using namespace Aws::Greengrass;

class SubscribeResponseHandler : public SubscribeToTopicStreamHandler {
    public:
        virtual ~SubscribeResponseHandler() {}

    private:
        void OnStreamEvent(SubscriptionResponseMessage *response) override {
            auto jsonMessage = response->GetJsonMessage();
            if (jsonMessage.has_value() && jsonMessage.value().GetMessage().has_value()) {
                auto messageString = jsonMessage.value().GetMessage().value().View().WriteReadable();
                // Handle JSON message.
            } else {
                auto binaryMessage = response->GetBinaryMessage();
                if (binaryMessage.has_value() && binaryMessage.value().GetMessage().has_value()) {
                    auto messageBytes = binaryMessage.value().GetMessage().value();
                    std::string messageString(messageBytes.begin(), messageBytes.end());
                    // Handle binary message.
                }
            }
        }

        bool OnStreamError(OperationError *error) override {
            // Handle error.
            return false; // Return true to close stream, false to keep stream open.
        }

        void OnStreamClosed() override {
            // Handle close.
        }
};

class IpcClientLifecycleHandler : public ConnectionLifecycleHandler {
    void OnConnectCallback() override {
        // Handle connection to IPC service.
    }

    void OnDisconnectCallback(RpcError error) override {
        // Handle disconnection from IPC service.
    }

    bool OnErrorCallback(RpcError error) override {
        // Handle IPC service connection error.
        return true;
    }
};

int main() {
    ApiHandle apiHandle(g_allocator);
    Io::EventLoopGroup eventLoopGroup(1);
    Io::DefaultHostResolver socketResolver(eventLoopGroup, 64, 30);
    Io::ClientBootstrap bootstrap(eventLoopGroup, socketResolver);
    IpcClientLifecycleHandler ipcLifecycleHandler;
    GreengrassCoreIpcClient ipcClient(bootstrap);
    auto connectionStatus = ipcClient.Connect(ipcLifecycleHandler).get();
    if (!connectionStatus) {
        std::cerr << "Failed to establish IPC connection: " << connectionStatus.StatusToString() << std::endl;
        exit(-1);
    }

    String topic("my/topic");
    int timeout = 10;

    SubscribeToTopicRequest request;
    request.SetTopic(topic);

    //SubscribeResponseHandler streamHandler;
    auto streamHandler = MakeShared<SubscribeResponseHandler>(DefaultAllocator());
    auto operation = ipcClient.NewSubscribeToTopic(streamHandler);
    auto activate = operation->Activate(request, nullptr);
    activate.wait();

    auto responseFuture = operation->GetResult();
    if (responseFuture.wait_for(std::chrono::seconds(timeout)) == std::future_status::timeout) {
        std::cerr << "Operation timed out while waiting for response from Greengrass Core." << std::endl;
        exit(-1);
    }

    auto response = responseFuture.get();
    if (!response) {
        // Handle error.
        auto errorType = response.GetResultType();
        if (errorType == OPERATION_ERROR) {
            auto *error = response.GetOperationError();
            (void)error;
            // Handle operation error.
        } else {
            // Handle RPC error.
        }
        exit(-1);
    }

    // Keep the main thread alive, or the process will exit.
    while (true) {
        std::this_thread::sleep_for(std::chrono::seconds(10));
    }

    operation->Close();
    return 0;
}
```

------
#### [ JavaScript ]

**Example Contoh: Berlangganan publish/subscribe pesan lokal**  <a name="ipc-operation-subscribetotopic-example-nodejs"></a>

```
import * as greengrasscoreipc from "aws-iot-device-sdk-v2/dist/greengrasscoreipc";
import {SubscribeToTopicRequest, SubscriptionResponseMessage} from "aws-iot-device-sdk-v2/dist/greengrasscoreipc/model";
import {RpcError} from "aws-iot-device-sdk-v2/dist/eventstream_rpc";
 
class SubscribeToTopic {
    private ipcClient : greengrasscoreipc.Client
    private readonly topic : string;
 
    constructor() {
        // define your own constructor, e.g.
        this.topic = "<define_your_topic>";
        this.subscribeToTopic().then(r => console.log("Started workflow"));
    }
 
    private async subscribeToTopic() {
        try {
            this.ipcClient = await getIpcClient();
 
            const subscribeToTopicRequest : SubscribeToTopicRequest = {
                topic: this.topic,
            }
 
            const streamingOperation = this.ipcClient.subscribeToTopic(subscribeToTopicRequest, undefined); // conditionally apply options
 
            streamingOperation.on("message", (message: SubscriptionResponseMessage) => {
                // parse the message depending on your use cases, e.g.
                if(message.binaryMessage && message.binaryMessage.message) {
                    const receivedMessage = message.binaryMessage?.message.toString();
                }
            });
 
            streamingOperation.on("streamError", (error : RpcError) => {
                // define your own error handling logic
            })
 
            streamingOperation.on("ended", () => {
                // define your own logic
            })
 
            await streamingOperation.activate();
 
            // Keep the main thread alive, or the process will exit.
            await new Promise((resolve) => setTimeout(resolve, 10000))
        } catch (e) {
            // parse the error depending on your use cases
            throw e
        }
    }
}
 
export async function getIpcClient(){
    try {
        const ipcClient = greengrasscoreipc.createClient();
        await ipcClient.connect()
            .catch(error => {
                // parse the error depending on your use cases
                throw error;
            });
        return ipcClient
    } catch (err) {
        // parse the error depending on your use cases
        throw err
    }
}
 
// starting point
const subscribeToTopic = new SubscribeToTopic();
```

------
#### [ Rust ]

**Example Contoh: Berlangganan publish/subscribe pesan lokal**  

```
use gg_sdk::{Sdk, SubscribeToTopicPayload};
use std::{thread, time::Duration};

fn main() {
    let sdk = Sdk::init();
    sdk.connect().expect("Failed to establish IPC connection");

    let topic = "my/topic";

    let callback = |topic: &str, payload: SubscribeToTopicPayload| match payload
    {
        SubscribeToTopicPayload::Binary(message) => {
            let message = String::from_utf8_lossy(message);
            println!("Received new message on topic {topic}: {message}");
        }
        SubscribeToTopicPayload::Json(_) => {
            println!("Received new message on topic {topic}: (JSON message)");
        }
    };

    let _sub = sdk
        .subscribe_to_topic(topic, &callback)
        .expect("Failed to subscribe to topic");

    println!("Successfully subscribed to topic: {topic}");

    // Keep the main thread alive, or the process will exit.
    loop {
        thread::sleep(Duration::from_secs(10));
    }
}
```

------
#### [ C ]

**Example Contoh: Berlangganan publish/subscribe pesan lokal**  

```
#include <assert.h>
#include <gg/error.h>
#include <gg/ipc/client.h>
#include <gg/object.h>
#include <gg/sdk.h>
#include <gg/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

static void on_subscription_response(
    void *ctx, GgBuffer topic, GgObject payload, GgIpcSubscriptionHandle handle
) {
    (void) ctx;
    (void) handle;

    if (gg_obj_type(payload) == GG_TYPE_BUF) {
        GgBuffer message = gg_obj_into_buf(payload);
        printf(
            "Received new message on topic %.*s: %.*s\n",
            (int) topic.len,
            topic.data,
            (int) message.len,
            message.data
        );
    } else {
        assert(gg_obj_type(payload) == GG_TYPE_MAP);
        printf(
            "Received new message on topic %.*s: (JSON message)\n",
            (int) topic.len,
            topic.data
        );
    }
}

int main(void) {
    gg_sdk_init();

    GgError err = ggipc_connect();
    if (err != GG_ERR_OK) {
        fprintf(stderr, "Failed to establish IPC connection.\n");
        exit(-1);
    }

    GgBuffer topic = GG_STR("my/topic");

    GgIpcSubscriptionHandle handle;
    err = ggipc_subscribe_to_topic(
        topic, on_subscription_response, NULL, &handle
    );
    if (err != GG_ERR_OK) {
        fprintf(
            stderr,
            "Failed to subscribe to topic: %.*s\n",
            (int) topic.len,
            topic.data
        );
        exit(-1);
    }

    printf(
        "Successfully subscribed to topic: %.*s\n", (int) topic.len, topic.data
    );

    // Keep the main thread alive, or the process will exit.
    while (1) {
        sleep(10);
    }

    // To stop subscribing, close the stream.
    ggipc_close_subscription(handle);
}
```

------
#### [ C\$1\$1 (Component SDK) ]

**Example Contoh: Berlangganan publish/subscribe pesan lokal**  

```
#include <gg/ipc/client.hpp>
#include <gg/object.hpp>
#include <unistd.h>
#include <cassert>
#include <iostream>

class ResponseHandler : public gg::ipc::LocalTopicCallback {
    void operator()(
        std::string_view topic,
        gg::Object payload,
        gg::ipc::Subscription &handle
    ) override {
        (void) handle;
        if (payload.index() == GG_TYPE_BUF) {
            std::cout << "Received new message on topic " << topic << ": "
                      << get<gg::Buffer>(payload) << "\n";
        } else {
            assert(payload.index() == GG_TYPE_MAP);
            std::cout << "Received new message on topic " << topic
                      << ": (JSON message)\n";
        }
    }
};

int main() {
    auto &client = gg::ipc::Client::get();

    auto error = client.connect();
    if (error) {
        std::cerr << "Failed to establish IPC connection.\n";
        exit(-1);
    }

    std::string_view topic = "my/topic";

    static ResponseHandler handler;
    error = client.subscribe_to_topic(topic, handler);
    if (error) {
        std::cerr << "Failed to subscribe to topic: " << topic << "\n";
        exit(-1);
    }

    std::cout << "Successfully subscribed to topic: " << topic << "\n";

    // Keep the main thread alive, or the process will exit.
    while (1) {
        sleep(10);
    }
}
```

------

## Contoh
<a name="ipc-publish-subscribe-examples"></a>

Gunakan contoh berikut untuk mempelajari cara menggunakan layanan publish/subscribe IPC di komponen Anda.

### Contoh publish/subscribe penerbit (Java, klien IPC V1)
<a name="ipc-publish-subscribe-example-publisher-java"></a>

Contoh resep berikut memungkinkan komponen untuk mempublikasikan ke semua topik.

------
#### [ JSON ]

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubPublisherJava",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that publishes messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubPublisherJava:pubsub:1": {
            "policyDescription": "Allows access to publish to all topics.",
            "operations": [
              "aws.greengrass#PublishToTopic"
            ],
            "resources": [
              "*"
            ]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Lifecycle": {
        "Run": "java -jar {artifacts:path}/PubSubPublisher.jar"
      }
    }
  ]
}
```

------
#### [ YAML ]

```
---
RecipeFormatVersion: '2020-01-25'
ComponentName: com.example.PubSubPublisherJava
ComponentVersion: '1.0.0'
ComponentDescription: A component that publishes messages.
ComponentPublisher: Amazon
ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ipc.pubsub:
        'com.example.PubSubPublisherJava:pubsub:1':
          policyDescription: Allows access to publish to all topics.
          operations:
            - 'aws.greengrass#PublishToTopic'
          resources:
            - '*'
Manifests:
  - Lifecycle:
      Run: |-
        java -jar {artifacts:path}/PubSubPublisher.jar
```

------

Aplikasi contoh Java berikut ini menunjukkan cara menggunakan layanan IPC publikasi/berlangganan untuk mempublikasikan pesan ke komponen lain.

```
/* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0 */

package com.example.ipc.pubsub;

import software.amazon.awssdk.aws.greengrass.GreengrassCoreIPCClient;
import software.amazon.awssdk.aws.greengrass.model.*;
import software.amazon.awssdk.eventstreamrpc.EventStreamRPCConnection;

import java.nio.charset.StandardCharsets;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class PubSubPublisher {

    public static void main(String[] args) {
        String message = "Hello from the pub/sub publisher (Java).";
        String topic = "test/topic/java";

        try (EventStreamRPCConnection eventStreamRPCConnection = IPCUtils.getEventStreamRpcConnection()) {
            GreengrassCoreIPCClient ipcClient = new GreengrassCoreIPCClient(eventStreamRPCConnection);

            while (true) {
                PublishToTopicRequest publishRequest = new PublishToTopicRequest();
                PublishMessage publishMessage = new PublishMessage();
                BinaryMessage binaryMessage = new BinaryMessage();
                binaryMessage.setMessage(message.getBytes(StandardCharsets.UTF_8));
                publishMessage.setBinaryMessage(binaryMessage);
                publishRequest.setPublishMessage(publishMessage);
                publishRequest.setTopic(topic);
                CompletableFuture<PublishToTopicResponse> futureResponse = ipcClient
                        .publishToTopic(publishRequest, Optional.empty()).getResponse();

                try {
                    futureResponse.get(10, TimeUnit.SECONDS);
                    System.out.println("Successfully published to topic: " + topic);
                } catch (TimeoutException e) {
                    System.err.println("Timeout occurred while publishing to topic: " + topic);
                } catch (ExecutionException e) {
                    if (e.getCause() instanceof UnauthorizedError) {
                        System.err.println("Unauthorized error while publishing to topic: " + topic);
                    } else {
                        System.err.println("Execution exception while publishing to topic: " + topic);
                    }
                    throw e;
                }
                Thread.sleep(5000);
            }
        } catch (InterruptedException e) {
            System.out.println("Publisher interrupted.");
        } catch (Exception e) {
            System.err.println("Exception occurred when using IPC.");
            e.printStackTrace();
            System.exit(1);
        }
    }
}
```

### Contoh publish/subscribe pelanggan (Java, klien IPC V1)
<a name="ipc-publish-subscribe-example-subscriber-java"></a>

Contoh resep berikut memungkinkan komponen untuk berlangganan semua topik.

------
#### [ JSON ]

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubSubscriberJava",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that subscribes to messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubSubscriberJava:pubsub:1": {
            "policyDescription": "Allows access to subscribe to all topics.",
            "operations": [
              "aws.greengrass#SubscribeToTopic"
            ],
            "resources": [
              "*"
            ]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Lifecycle": {
        "Run": "java -jar {artifacts:path}/PubSubSubscriber.jar"
      }
    }
  ]
}
```

------
#### [ YAML ]

```
---
RecipeFormatVersion: '2020-01-25'
ComponentName: com.example.PubSubSubscriberJava
ComponentVersion: '1.0.0'
ComponentDescription: A component that subscribes to messages.
ComponentPublisher: Amazon
ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ipc.pubsub:
        'com.example.PubSubSubscriberJava:pubsub:1':
          policyDescription: Allows access to subscribe to all topics.
          operations:
            - 'aws.greengrass#SubscribeToTopic'
          resources:
            - '*'
Manifests:
  - Lifecycle:
      Run: |-
        java -jar {artifacts:path}/PubSubSubscriber.jar
```

------

Aplikasi contoh Java berikut ini menunjukkan cara menggunakan layanan IPC publikasi/berlangganan untuk berlangganan pesan ke komponen lain.

```
/* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0 */

package com.example.ipc.pubsub;

import software.amazon.awssdk.aws.greengrass.GreengrassCoreIPCClient;
import software.amazon.awssdk.aws.greengrass.SubscribeToTopicResponseHandler;
import software.amazon.awssdk.aws.greengrass.model.SubscribeToTopicRequest;
import software.amazon.awssdk.aws.greengrass.model.SubscribeToTopicResponse;
import software.amazon.awssdk.aws.greengrass.model.SubscriptionResponseMessage;
import software.amazon.awssdk.aws.greengrass.model.UnauthorizedError;
import software.amazon.awssdk.eventstreamrpc.EventStreamRPCConnection;
import software.amazon.awssdk.eventstreamrpc.StreamResponseHandler;

import java.nio.charset.StandardCharsets;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class PubSubSubscriber {

    public static void main(String[] args) {
        String topic = "test/topic/java";

        try (EventStreamRPCConnection eventStreamRPCConnection = IPCUtils.getEventStreamRpcConnection()) {
            GreengrassCoreIPCClient ipcClient = new GreengrassCoreIPCClient(eventStreamRPCConnection);

            SubscribeToTopicRequest subscribeRequest = new SubscribeToTopicRequest();
            subscribeRequest.setTopic(topic);
            SubscribeToTopicResponseHandler operationResponseHandler = ipcClient
                    .subscribeToTopic(subscribeRequest, Optional.of(new SubscribeResponseHandler()));
            CompletableFuture<SubscribeToTopicResponse> futureResponse = operationResponseHandler.getResponse();

            try {
                futureResponse.get(10, TimeUnit.SECONDS);
                System.out.println("Successfully subscribed to topic: " + topic);
            } catch (TimeoutException e) {
                System.err.println("Timeout occurred while subscribing to topic: " + topic);
                throw e;
            } catch (ExecutionException e) {
                if (e.getCause() instanceof UnauthorizedError) {
                    System.err.println("Unauthorized error while subscribing to topic: " + topic);
                } else {
                    System.err.println("Execution exception while subscribing to topic: " + topic);
                }
                throw e;
            }

            // Keep the main thread alive, or the process will exit.
            try {
                while (true) {
                    Thread.sleep(10000);
                }
            } catch (InterruptedException e) {
                System.out.println("Subscribe interrupted.");
            }
        } catch (Exception e) {
            System.err.println("Exception occurred when using IPC.");
            e.printStackTrace();
            System.exit(1);
        }
    }

    private static class SubscribeResponseHandler implements StreamResponseHandler<SubscriptionResponseMessage> {

        @Override
        public void onStreamEvent(SubscriptionResponseMessage subscriptionResponseMessage) {
            try {
                String message = new String(subscriptionResponseMessage.getBinaryMessage()
                        .getMessage(), StandardCharsets.UTF_8);
                System.out.println("Received new message: " + message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        @Override
        public boolean onStreamError(Throwable error) {
            System.err.println("Received a stream error.");
            error.printStackTrace();
            return false; // Return true to close stream, false to keep stream open.
        }

        @Override
        public void onStreamClosed() {
            System.out.println("Subscribe to topic stream closed.");
        }
    }
}
```

### Contoh publish/subscribe penerbit (Python, klien IPC V1)
<a name="ipc-publish-subscribe-example-publisher-python"></a>

Contoh resep berikut memungkinkan komponen untuk mempublikasikan ke semua topik.

------
#### [ JSON ]

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubPublisherPython",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that publishes messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubPublisherPython:pubsub:1": {
            "policyDescription": "Allows access to publish to all topics.",
            "operations": [
              "aws.greengrass#PublishToTopic"
            ],
            "resources": [
              "*"
            ]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux"
      },
      "Lifecycle": {
        "install": "python3 -m pip install --user awsiotsdk",
        "Run": "python3 -u {artifacts:path}/pubsub_publisher.py"
      }
    },
    {
      "Platform": {
        "os": "windows"
      },
      "Lifecycle": {
        "install": "py -3 -m pip install --user awsiotsdk",
        "Run": "py -3 -u {artifacts:path}/pubsub_publisher.py"
      }
    }
  ]
}
```

------
#### [ YAML ]

```
---
RecipeFormatVersion: '2020-01-25'
ComponentName: com.example.PubSubPublisherPython
ComponentVersion: 1.0.0
ComponentDescription: A component that publishes messages.
ComponentPublisher: Amazon
ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ipc.pubsub:
        com.example.PubSubPublisherPython:pubsub:1:
          policyDescription: Allows access to publish to all topics.
          operations:
            - aws.greengrass#PublishToTopic
          resources:
            - "*"
Manifests:
  - Platform:
      os: linux
    Lifecycle:
      install: python3 -m pip install --user awsiotsdk
      Run: python3 -u {artifacts:path}/pubsub_publisher.py
  - Platform:
      os: windows
    Lifecycle:
      install: py -3 -m pip install --user awsiotsdk
      Run: py -3 -u {artifacts:path}/pubsub_publisher.py
```

------

Aplikasi contoh Python berikut ini menunjukkan cara menggunakan layanan IPC publikasi/berlangganan untuk mempublikasikan pesan ke komponen lain.

```
import concurrent.futures
import sys
import time
import traceback

import awsiot.greengrasscoreipc
from awsiot.greengrasscoreipc.model import (
    PublishToTopicRequest,
    PublishMessage,
    BinaryMessage,
    UnauthorizedError
)

                    
topic = "test/topic/python"
message = "Hello from the pub/sub publisher (Python)."
TIMEOUT = 10

try:
    ipc_client = awsiot.greengrasscoreipc.connect()

    while True:
        request = PublishToTopicRequest()
        request.topic = topic
        publish_message = PublishMessage()
        publish_message.binary_message = BinaryMessage()
        publish_message.binary_message.message = bytes(message, "utf-8")
        request.publish_message = publish_message
        operation = ipc_client.new_publish_to_topic()
        operation.activate(request)
        future_response = operation.get_response()

        try:
            future_response.result(TIMEOUT)
            print('Successfully published to topic: ' + topic)
        except concurrent.futures.TimeoutError:
            print('Timeout occurred while publishing to topic: ' + topic, file=sys.stderr)
        except UnauthorizedError as e:
            print('Unauthorized error while publishing to topic: ' + topic, file=sys.stderr)
            raise e
        except Exception as e:
            print('Exception while publishing to topic: ' + topic, file=sys.stderr)
            raise e
        time.sleep(5)
except InterruptedError:
    print('Publisher interrupted.')
except Exception:
    print('Exception occurred when using IPC.', file=sys.stderr)
    traceback.print_exc()
    exit(1)
```

### Contoh publish/subscribe pelanggan (Python, klien IPC V1)
<a name="ipc-publish-subscribe-example-subscriber-python"></a>

Contoh resep berikut memungkinkan komponen untuk berlangganan semua topik.

------
#### [ JSON ]

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubSubscriberPython",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that subscribes to messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubSubscriberPython:pubsub:1": {
            "policyDescription": "Allows access to subscribe to all topics.",
            "operations": [
              "aws.greengrass#SubscribeToTopic"
            ],
            "resources": [
              "*"
            ]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux"
      },
      "Lifecycle": {
        "install": "python3 -m pip install --user awsiotsdk",
        "Run": "python3 -u {artifacts:path}/pubsub_subscriber.py"
      }
    },
    {
      "Platform": {
        "os": "windows"
      },
      "Lifecycle": {
        "install": "py -3 -m pip install --user awsiotsdk",
        "Run": "py -3 -u {artifacts:path}/pubsub_subscriber.py"
      }
    }
  ]
}
```

------
#### [ YAML ]

```
---
RecipeFormatVersion: '2020-01-25'
ComponentName: com.example.PubSubSubscriberPython
ComponentVersion: 1.0.0
ComponentDescription: A component that subscribes to messages.
ComponentPublisher: Amazon
ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ipc.pubsub:
        com.example.PubSubSubscriberPython:pubsub:1:
          policyDescription: Allows access to subscribe to all topics.
          operations:
            - aws.greengrass#SubscribeToTopic
          resources:
            - "*"
Manifests:
  - Platform:
      os: linux
    Lifecycle:
      install: python3 -m pip install --user awsiotsdk
      Run: python3 -u {artifacts:path}/pubsub_subscriber.py
  - Platform:
      os: windows
    Lifecycle:
      install: py -3 -m pip install --user awsiotsdk
      Run: py -3 -u {artifacts:path}/pubsub_subscriber.py
```

------

Aplikasi contoh Python berikut ini menunjukkan cara menggunakan layanan IPC publikasi/berlangganan untuk berlangganan pesan ke komponen lain.

```
import concurrent.futures
import sys
import time
import traceback

import awsiot.greengrasscoreipc
import awsiot.greengrasscoreipc.client as client
from awsiot.greengrasscoreipc.model import (
    SubscribeToTopicRequest,
    SubscriptionResponseMessage,
    UnauthorizedError
)

topic = "test/topic/python"
TIMEOUT = 10

                    
class StreamHandler(client.SubscribeToTopicStreamHandler):
    def __init__(self):
        super().__init__()

    def on_stream_event(self, event: SubscriptionResponseMessage) -> None:
        try:
            message = str(event.binary_message.message, "utf-8")
            print("Received new message: " + message)
        except:
            traceback.print_exc()

    def on_stream_error(self, error: Exception) -> bool:
        print("Received a stream error.", file=sys.stderr)
        traceback.print_exc()
        return False  # Return True to close stream, False to keep stream open.

    def on_stream_closed(self) -> None:
        print('Subscribe to topic stream closed.')


try:
    ipc_client = awsiot.greengrasscoreipc.connect()

    request = SubscribeToTopicRequest()
    request.topic = topic
    handler = StreamHandler()
    operation = ipc_client.new_subscribe_to_topic(handler)
    operation.activate(request)
    future_response = operation.get_response()
    
    try:
        future_response.result(TIMEOUT)
        print('Successfully subscribed to topic: ' + topic)
    except concurrent.futures.TimeoutError as e:
        print('Timeout occurred while subscribing to topic: ' + topic, file=sys.stderr)
        raise e
    except UnauthorizedError as e:
        print('Unauthorized error while subscribing to topic: ' + topic, file=sys.stderr)
        raise e
    except Exception as e:
        print('Exception while subscribing to topic: ' + topic, file=sys.stderr)
        raise e

    # Keep the main thread alive, or the process will exit.
    try:
        while True:
            time.sleep(10)
    except InterruptedError:
        print('Subscribe interrupted.')
except Exception:
    print('Exception occurred when using IPC.', file=sys.stderr)
    traceback.print_exc()
    exit(1)
```

### Contoh publish/subscribe penerbit (C \$1\$1, klien IPC V1)
<a name="ipc-publish-subscribe-example-publisher-cpp"></a>

Contoh resep berikut memungkinkan komponen untuk mempublikasikan ke semua topik.

------
#### [ JSON ]

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubPublisherCpp",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that publishes messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubPublisherCpp:pubsub:1": {
            "policyDescription": "Allows access to publish to all topics.",
            "operations": [
              "aws.greengrass#PublishToTopic"
            ],
            "resources": [
              "*"
            ]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Lifecycle": {
        "Run": "{artifacts:path}/greengrassv2_pubsub_publisher"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubPublisherCpp/1.0.0/greengrassv2_pubsub_publisher",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

------
#### [ YAML ]

```
---
RecipeFormatVersion: '2020-01-25'
ComponentName: com.example.PubSubPublisherCpp
ComponentVersion: 1.0.0
ComponentDescription: A component that publishes messages.
ComponentPublisher: Amazon
ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ipc.pubsub:
        com.example.PubSubPublisherCpp:pubsub:1:
          policyDescription: Allows access to publish to all topics.
          operations:
            - aws.greengrass#PublishToTopic
          resources:
            - "*"
Manifests:
  - Lifecycle:
      Run: "{artifacts:path}/greengrassv2_pubsub_publisher"
    Artifacts:
      - URI: s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubPublisherCpp/1.0.0/greengrassv2_pubsub_publisher
        Permission:
          Execute: OWNER
```

------

Aplikasi contoh C\$1\$1 berikut ini menunjukkan cara menggunakan layanan IPC publikasi/berlangganan untuk mempublikasikan pesan ke komponen lain.

```
#include <iostream>

#include <aws/crt/Api.h>
#include <aws/greengrass/GreengrassCoreIpcClient.h>

using namespace Aws::Crt;
using namespace Aws::Greengrass;

class IpcClientLifecycleHandler : public ConnectionLifecycleHandler {
    void OnConnectCallback() override {
        std::cout << "OnConnectCallback" << std::endl;
    }

    void OnDisconnectCallback(RpcError error) override {
        std::cout << "OnDisconnectCallback: " << error.StatusToString() << std::endl;
        exit(-1);
    }

    bool OnErrorCallback(RpcError error) override {
        std::cout << "OnErrorCallback: " << error.StatusToString() << std::endl;
        return true;
    }
};

int main() {
    String message("Hello from the pub/sub publisher (C++).");
    String topic("test/topic/cpp");
    int timeout = 10;

    ApiHandle apiHandle(g_allocator);
    Io::EventLoopGroup eventLoopGroup(1);
    Io::DefaultHostResolver socketResolver(eventLoopGroup, 64, 30);
    Io::ClientBootstrap bootstrap(eventLoopGroup, socketResolver);
    IpcClientLifecycleHandler ipcLifecycleHandler;
    GreengrassCoreIpcClient ipcClient(bootstrap);
    auto connectionStatus = ipcClient.Connect(ipcLifecycleHandler).get();
    if (!connectionStatus) {
        std::cerr << "Failed to establish IPC connection: " << connectionStatus.StatusToString() << std::endl;
        exit(-1);
    }

    while (true) {
        PublishToTopicRequest request;
        Vector<uint8_t> messageData({message.begin(), message.end()});
        BinaryMessage binaryMessage;
        binaryMessage.SetMessage(messageData);
        PublishMessage publishMessage;
        publishMessage.SetBinaryMessage(binaryMessage);
        request.SetTopic(topic);
        request.SetPublishMessage(publishMessage);

        auto operation = ipcClient.NewPublishToTopic();
        auto activate = operation->Activate(request, nullptr);
        activate.wait();

        auto responseFuture = operation->GetResult();
        if (responseFuture.wait_for(std::chrono::seconds(timeout)) == std::future_status::timeout) {
            std::cerr << "Operation timed out while waiting for response from Greengrass Core." << std::endl;
            exit(-1);
        }

        auto response = responseFuture.get();
        if (response) {
            std::cout << "Successfully published to topic: " << topic << std::endl;
        } else {
            // An error occurred.
            std::cout << "Failed to publish to topic: " << topic << std::endl;
            auto errorType = response.GetResultType();
            if (errorType == OPERATION_ERROR) {
                auto *error = response.GetOperationError();
                std::cout << "Operation error: " << error->GetMessage().value() << std::endl;
            } else {
                std::cout << "RPC error: " << response.GetRpcError() << std::endl;
            }
            exit(-1);
        }

        std::this_thread::sleep_for(std::chrono::seconds(5));
    }

    return 0;
}
```

### Contoh publish/subscribe pelanggan (C \$1\$1, klien IPC V1)
<a name="ipc-publish-subscribe-example-subscriber-cpp"></a>

Contoh resep berikut memungkinkan komponen untuk berlangganan semua topik.

------
#### [ JSON ]

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubSubscriberCpp",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that subscribes to messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubSubscriberCpp:pubsub:1": {
            "policyDescription": "Allows access to subscribe to all topics.",
            "operations": [
              "aws.greengrass#SubscribeToTopic"
            ],
            "resources": [
              "*"
            ]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Lifecycle": {
        "Run": "{artifacts:path}/greengrassv2_pub_sub_subscriber"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubSubscriberCpp/1.0.0/greengrassv2_pub_sub_subscriber",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

------
#### [ YAML ]

```
---
RecipeFormatVersion: '2020-01-25'
ComponentName: com.example.PubSubSubscriberCpp
ComponentVersion: 1.0.0
ComponentDescription: A component that subscribes to messages.
ComponentPublisher: Amazon
ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ipc.pubsub:
        com.example.PubSubSubscriberCpp:pubsub:1:
          policyDescription: Allows access to subscribe to all topics.
          operations:
            - aws.greengrass#SubscribeToTopic
          resources:
            - "*"
Manifests:
  - Lifecycle:
      Run: "{artifacts:path}/greengrassv2_pub_sub_subscriber"
    Artifacts:
      - URI: s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubSubscriberCpp/1.0.0/greengrassv2_pub_sub_subscriber
        Permission:
          Execute: OWNER
```

------

Aplikasi contoh C\$1\$1 berikut ini menunjukkan cara menggunakan layanan IPC publikasi/berlangganan untuk berlangganan pesan ke komponen lain.

```
#include <iostream>

#include <aws/crt/Api.h>
#include <aws/greengrass/GreengrassCoreIpcClient.h>

using namespace Aws::Crt;
using namespace Aws::Greengrass;

class SubscribeResponseHandler : public SubscribeToTopicStreamHandler {
    public:
        virtual ~SubscribeResponseHandler() {}

    private:
        void OnStreamEvent(SubscriptionResponseMessage *response) override {
            auto jsonMessage = response->GetJsonMessage();
            if (jsonMessage.has_value() && jsonMessage.value().GetMessage().has_value()) {
                auto messageString = jsonMessage.value().GetMessage().value().View().WriteReadable();
                std::cout << "Received new message: " << messageString << std::endl;
            } else {
                auto binaryMessage = response->GetBinaryMessage();
                if (binaryMessage.has_value() && binaryMessage.value().GetMessage().has_value()) {
                    auto messageBytes = binaryMessage.value().GetMessage().value();
                    std::string messageString(messageBytes.begin(), messageBytes.end());
                    std::cout << "Received new message: " << messageString << std::endl;
                }
            }
        }

        bool OnStreamError(OperationError *error) override {
            std::cout << "Received an operation error: ";
            if (error->GetMessage().has_value()) {
                std::cout << error->GetMessage().value();
            }
            std::cout << std::endl;
            return false; // Return true to close stream, false to keep stream open.
        }

        void OnStreamClosed() override {
            std::cout << "Subscribe to topic stream closed." << std::endl;
        }
};

class IpcClientLifecycleHandler : public ConnectionLifecycleHandler {
    void OnConnectCallback() override {
        std::cout << "OnConnectCallback" << std::endl;
    }

    void OnDisconnectCallback(RpcError error) override {
        std::cout << "OnDisconnectCallback: " << error.StatusToString() << std::endl;
        exit(-1);
    }

    bool OnErrorCallback(RpcError error) override {
        std::cout << "OnErrorCallback: " << error.StatusToString() << std::endl;
        return true;
    }
};

int main() {
    String topic("test/topic/cpp");
    int timeout = 10;

    ApiHandle apiHandle(g_allocator);
    Io::EventLoopGroup eventLoopGroup(1);
    Io::DefaultHostResolver socketResolver(eventLoopGroup, 64, 30);
    Io::ClientBootstrap bootstrap(eventLoopGroup, socketResolver);
    IpcClientLifecycleHandler ipcLifecycleHandler;
    GreengrassCoreIpcClient ipcClient(bootstrap);
    auto connectionStatus = ipcClient.Connect(ipcLifecycleHandler).get();
    if (!connectionStatus) {
        std::cerr << "Failed to establish IPC connection: " << connectionStatus.StatusToString() << std::endl;
        exit(-1);
    }

    SubscribeToTopicRequest request;
    request.SetTopic(topic);
    auto streamHandler = MakeShared<SubscribeResponseHandler>(DefaultAllocator());
    auto operation = ipcClient.NewSubscribeToTopic(streamHandler);
    auto activate = operation->Activate(request, nullptr);
    activate.wait();

    auto responseFuture = operation->GetResult();
    if (responseFuture.wait_for(std::chrono::seconds(timeout)) == std::future_status::timeout) {
        std::cerr << "Operation timed out while waiting for response from Greengrass Core." << std::endl;
        exit(-1);
    }

    auto response = responseFuture.get();
    if (response) {
        std::cout << "Successfully subscribed to topic: " << topic << std::endl;
    } else {
        // An error occurred.
        std::cout << "Failed to subscribe to topic: " << topic << std::endl;
        auto errorType = response.GetResultType();
        if (errorType == OPERATION_ERROR) {
            auto *error = response.GetOperationError();
            std::cout << "Operation error: " << error->GetMessage().value() << std::endl;
        } else {
            std::cout << "RPC error: " << response.GetRpcError() << std::endl;
        }
        exit(-1);
    }

    // Keep the main thread alive, or the process will exit.
    while (true) {
        std::this_thread::sleep_for(std::chrono::seconds(10));
    }

    operation->Close();
    return 0;
}
```

### Contoh publish/subscribe penerbit (Rust)
<a name="ipc-publish-subscribe-example-publisher-rust"></a>

Contoh resep berikut memungkinkan komponen untuk mempublikasikan ke semua topik.

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubPublisherRust",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that publishes messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubPublisherRust:pubsub:1": {
            "policyDescription": "Allows access to publish to all topics.",
            "operations": ["aws.greengrass#PublishToTopic"],
            "resources": ["*"]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux",
        "runtime": "*"
      },
      "Lifecycle": {
        "run": "{artifacts:path}/publish_to_topic"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubPublisherRust/1.0.0/publish_to_topic",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

Contoh berikut aplikasi Rust menunjukkan bagaimana menggunakan layanan IPC terbitkan/berlangganan untuk mempublikasikan pesan ke komponen lain.

```
use gg_sdk::Sdk;

fn main() {
    let sdk = Sdk::init();
    sdk.connect().expect("Failed to establish IPC connection");

    let message = b"Hello, World";
    let topic = "my/topic";

    sdk.publish_to_topic_binary(topic, message)
        .expect("Failed to publish to topic");

    println!("Successfully published to topic: {topic}");
}
```

### Contoh publish/subscribe pelanggan (Rust)
<a name="ipc-publish-subscribe-example-subscriber-rust"></a>

Contoh resep berikut memungkinkan komponen untuk berlangganan semua topik.

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubSubscriberRust",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that subscribes to messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubSubscriberRust:pubsub:1": {
            "policyDescription": "Allows access to subscribe to all topics.",
            "operations": ["aws.greengrass#SubscribeToTopic"],
            "resources": ["*"]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux",
        "runtime": "*"
      },
      "Lifecycle": {
        "run": "{artifacts:path}/subscribe_to_topic"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubSubscriberRust/1.0.0/subscribe_to_topic",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

Contoh berikut aplikasi Rust menunjukkan cara menggunakan layanan IPC terbitkan/berlangganan untuk berlangganan pesan dari komponen lain.

```
use gg_sdk::{Sdk, SubscribeToTopicPayload};
use std::{thread, time::Duration};

fn main() {
    let sdk = Sdk::init();
    sdk.connect().expect("Failed to establish IPC connection");

    let topic = "my/topic";

    let callback = |topic: &str, payload: SubscribeToTopicPayload| match payload
    {
        SubscribeToTopicPayload::Binary(message) => {
            let message = String::from_utf8_lossy(message);
            println!("Received new message on topic {topic}: {message}");
        }
        SubscribeToTopicPayload::Json(_) => {
            println!("Received new message on topic {topic}: (JSON message)");
        }
    };

    let _sub = sdk
        .subscribe_to_topic(topic, &callback)
        .expect("Failed to subscribe to topic");

    println!("Successfully subscribed to topic: {topic}");

    // Keep the main thread alive, or the process will exit.
    loop {
        thread::sleep(Duration::from_secs(10));
    }
}
```

### Contoh publish/subscribe penerbit (C)
<a name="ipc-publish-subscribe-example-publisher-c"></a>

Contoh resep berikut memungkinkan komponen untuk mempublikasikan ke semua topik.

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubPublisherC",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that publishes messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubPublisherC:pubsub:1": {
            "policyDescription": "Allows access to publish to all topics.",
            "operations": ["aws.greengrass#PublishToTopic"],
            "resources": ["*"]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux",
        "runtime": "*"
      },
      "Lifecycle": {
        "run": "{artifacts:path}/sample_publish_to_topic"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubPublisherC/1.0.0/sample_publish_to_topic",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

Contoh berikut C aplikasi menunjukkan bagaimana menggunakan layanan IPC terbitkan/berlangganan untuk mempublikasikan pesan ke komponen lain.

```
#include <gg/error.h>
#include <gg/ipc/client.h>
#include <gg/sdk.h>
#include <stdio.h>
#include <stdlib.h>

int main(void) {
    gg_sdk_init();

    GgError err = ggipc_connect();
    if (err != GG_ERR_OK) {
        fprintf(stderr, "Failed to establish IPC connection.\n");
        exit(-1);
    }

    GgBuffer message = GG_STR("Hello, World");
    GgBuffer topic = GG_STR("my/topic");

    err = ggipc_publish_to_topic_binary(topic, message);
    if (err != GG_ERR_OK) {
        fprintf(
            stderr,
            "Failed to publish to topic: %.*s\n",
            (int) topic.len,
            topic.data
        );
        exit(-1);
    }

    printf(
        "Successfully published to topic: %.*s\n", (int) topic.len, topic.data
    );
}
```

### Contoh publish/subscribe pelanggan (C)
<a name="ipc-publish-subscribe-example-subscriber-c"></a>

Contoh resep berikut memungkinkan komponen untuk berlangganan semua topik.

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubSubscriberC",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that subscribes to messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubSubscriberC:pubsub:1": {
            "policyDescription": "Allows access to subscribe to all topics.",
            "operations": ["aws.greengrass#SubscribeToTopic"],
            "resources": ["*"]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux",
        "runtime": "*"
      },
      "Lifecycle": {
        "run": "{artifacts:path}/sample_subscribe_to_topic"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubSubscriberC/1.0.0/sample_subscribe_to_topic",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

Contoh berikut C aplikasi menunjukkan bagaimana menggunakan layanan IPC terbitkan/berlangganan untuk berlangganan pesan dari komponen lain.

```
#include <assert.h>
#include <gg/error.h>
#include <gg/ipc/client.h>
#include <gg/object.h>
#include <gg/sdk.h>
#include <gg/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

static void on_subscription_response(
    void *ctx, GgBuffer topic, GgObject payload, GgIpcSubscriptionHandle handle
) {
    (void) ctx;
    (void) handle;

    if (gg_obj_type(payload) == GG_TYPE_BUF) {
        GgBuffer message = gg_obj_into_buf(payload);
        printf(
            "Received new message on topic %.*s: %.*s\n",
            (int) topic.len,
            topic.data,
            (int) message.len,
            message.data
        );
    } else {
        assert(gg_obj_type(payload) == GG_TYPE_MAP);
        printf(
            "Received new message on topic %.*s: (JSON message)\n",
            (int) topic.len,
            topic.data
        );
    }
}

int main(void) {
    gg_sdk_init();

    GgError err = ggipc_connect();
    if (err != GG_ERR_OK) {
        fprintf(stderr, "Failed to establish IPC connection.\n");
        exit(-1);
    }

    GgBuffer topic = GG_STR("my/topic");

    GgIpcSubscriptionHandle handle;
    err = ggipc_subscribe_to_topic(
        topic, on_subscription_response, NULL, &handle
    );
    if (err != GG_ERR_OK) {
        fprintf(
            stderr,
            "Failed to subscribe to topic: %.*s\n",
            (int) topic.len,
            topic.data
        );
        exit(-1);
    }

    printf(
        "Successfully subscribed to topic: %.*s\n", (int) topic.len, topic.data
    );

    // Keep the main thread alive, or the process will exit.
    while (1) {
        sleep(10);
    }

    // To stop subscribing, close the stream.
    ggipc_close_subscription(handle);
}
```

### Contoh publish/subscribe penerbit (C \$1\$1, SDK Komponen)
<a name="ipc-publish-subscribe-example-publisher-cpp-component-sdk"></a>

Contoh resep berikut memungkinkan komponen untuk mempublikasikan ke semua topik.

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubPublisherCpp",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that publishes messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubPublisherCpp:pubsub:1": {
            "policyDescription": "Allows access to publish to all topics.",
            "operations": ["aws.greengrass#PublishToTopic"],
            "resources": ["*"]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux",
        "runtime": "*"
      },
      "Lifecycle": {
        "run": "{artifacts:path}/sample_cpp_publish_to_topic"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubPublisherCpp/1.0.0/sample_cpp_publish_to_topic",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

Aplikasi contoh C\$1\$1 berikut ini menunjukkan cara menggunakan layanan IPC publikasi/berlangganan untuk mempublikasikan pesan ke komponen lain.

```
#include <gg/ipc/client.hpp>
#include <iostream>

int main() {
    auto &client = gg::ipc::Client::get();

    auto error = client.connect();
    if (error) {
        std::cerr << "Failed to establish IPC connection.\n";
        exit(-1);
    }

    std::string_view message = "Hello, World";
    std::string_view topic = "my/topic";

    error = client.publish_to_topic(topic, message);
    if (error) {
        std::cerr << "Failed to publish to topic: " << topic << "\n";
        exit(-1);
    }

    std::cout << "Successfully published to topic: " << topic << "\n";
}
```

### Contoh publish/subscribe pelanggan (C \$1\$1, Component SDK)
<a name="ipc-publish-subscribe-example-subscriber-cpp-component-sdk"></a>

Contoh resep berikut memungkinkan komponen untuk berlangganan semua topik.

```
{
  "RecipeFormatVersion": "2020-01-25",
  "ComponentName": "com.example.PubSubSubscriberCpp",
  "ComponentVersion": "1.0.0",
  "ComponentDescription": "A component that subscribes to messages.",
  "ComponentPublisher": "Amazon",
  "ComponentConfiguration": {
    "DefaultConfiguration": {
      "accessControl": {
        "aws.greengrass.ipc.pubsub": {
          "com.example.PubSubSubscriberCpp:pubsub:1": {
            "policyDescription": "Allows access to subscribe to all topics.",
            "operations": ["aws.greengrass#SubscribeToTopic"],
            "resources": ["*"]
          }
        }
      }
    }
  },
  "Manifests": [
    {
      "Platform": {
        "os": "linux",
        "runtime": "*"
      },
      "Lifecycle": {
        "run": "{artifacts:path}/sample_cpp_subscribe_to_topic"
      },
      "Artifacts": [
        {
          "URI": "s3://amzn-s3-demo-bucket/artifacts/com.example.PubSubSubscriberCpp/1.0.0/sample_cpp_subscribe_to_topic",
          "Permission": {
            "Execute": "OWNER"
          }
        }
      ]
    }
  ]
}
```

Contoh berikut aplikasi C\$1\$1 menunjukkan bagaimana menggunakan layanan IPC terbitkan/berlangganan untuk berlangganan pesan dari komponen lain.

```
#include <gg/ipc/client.hpp>
#include <gg/object.hpp>
#include <unistd.h>
#include <cassert>
#include <iostream>

class ResponseHandler : public gg::ipc::LocalTopicCallback {
    void operator()(
        std::string_view topic,
        gg::Object payload,
        gg::ipc::Subscription &handle
    ) override {
        (void) handle;
        if (payload.index() == GG_TYPE_BUF) {
            std::cout << "Received new message on topic " << topic << ": "
                      << get<gg::Buffer>(payload) << "\n";
        } else {
            assert(payload.index() == GG_TYPE_MAP);
            std::cout << "Received new message on topic " << topic
                      << ": (JSON message)\n";
        }
    }
};

int main() {
    auto &client = gg::ipc::Client::get();

    auto error = client.connect();
    if (error) {
        std::cerr << "Failed to establish IPC connection.\n";
        exit(-1);
    }

    std::string_view topic = "my/topic";

    static ResponseHandler handler;
    error = client.subscribe_to_topic(topic, handler);
    if (error) {
        std::cerr << "Failed to subscribe to topic: " << topic << "\n";
        exit(-1);
    }

    std::cout << "Successfully subscribed to topic: " << topic << "\n";

    // Keep the main thread alive, or the process will exit.
    while (1) {
        sleep(10);
    }
}
```