AWS SDK Version 4 for .NET
API Reference

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Container for the parameters to the InitiateMultipartUpload operation. This action initiates a multipart upload and returns an upload ID. This upload ID is used to associate all of the parts in the specific multipart upload. You specify this upload ID in each of your subsequent upload part requests (see UploadPart). You also include this upload ID in the final request to either complete or abort the multipart upload request. For more information about multipart uploads, see Multipart Upload Overview in the Amazon S3 User Guide.

After you initiate a multipart upload and upload one or more parts, to stop being charged for storing the uploaded parts, you must either complete or abort the multipart upload. Amazon S3 frees up the space used to store the parts and stops charging you for storing them only after you either complete or abort a multipart upload.

If you have configured a lifecycle rule to abort incomplete multipart uploads, the created multipart upload must be completed within the number of days specified in the bucket lifecycle configuration. Otherwise, the incomplete multipart upload becomes eligible for an abort action and Amazon S3 aborts the multipart upload. For more information, see Aborting Incomplete Multipart Uploads Using a Bucket Lifecycle Configuration.

  • Directory buckets - S3 Lifecycle is not supported by directory buckets.

  • Directory buckets - For directory buckets, you must make requests for this API operation to the Zonal endpoint. These endpoints support virtual-hosted-style requests in the format https://bucket_name.s3express-az_id.region.amazonaws.com/key-name. Path-style requests are not supported. For more information, see Regional and Zonal endpoints in the Amazon S3 User Guide.

Request signing

For request signing, multipart upload is just a series of regular requests. You initiate a multipart upload, send one or more requests to upload parts, and then complete the multipart upload process. You sign each request individually. There is nothing special about signing multipart upload requests. For more information about signing, see Authenticating Requests (Amazon Web Services Signature Version 4) in the Amazon S3 User Guide.

Permissions

  • General purpose bucket permissions - For information about the permissions required to use the multipart upload API, see Multipart upload and permissions in the Amazon S3 User Guide.

    To perform a multipart upload with encryption by using an Amazon Web Services KMS key, the requester must have permission to the kms:Decrypt and kms:GenerateDataKey* actions on the key. These permissions are required because Amazon S3 must decrypt and read data from the encrypted file parts before it completes the multipart upload. For more information, see Multipart upload API and permissions and Protecting data using server-side encryption with Amazon Web Services KMS in the Amazon S3 User Guide.

  • Directory bucket permissions - To grant access to this API operation on a directory bucket, we recommend that you use the CreateSession API operation for session-based authorization. Specifically, you grant the s3express:CreateSession permission to the directory bucket in a bucket policy or an IAM identity-based policy. Then, you make the CreateSession API call on the bucket to obtain a session token. With the session token in your request header, you can make API requests to this operation. After the session token expires, you make another CreateSession API call to generate a new session token for use. Amazon Web Services CLI or SDKs create session and refresh the session token automatically to avoid service interruptions when a session expires. For more information about authorization, see CreateSession.

Encryption

  • General purpose buckets - Server-side encryption is for data encryption at rest. Amazon S3 encrypts your data as it writes it to disks in its data centers and decrypts it when you access it. Amazon S3 automatically encrypts all new objects that are uploaded to an S3 bucket. When doing a multipart upload, if you don't specify encryption information in your request, the encryption setting of the uploaded parts is set to the default encryption configuration of the destination bucket. By default, all buckets have a base level of encryption configuration that uses server-side encryption with Amazon S3 managed keys (SSE-S3). If the destination bucket has a default encryption configuration that uses server-side encryption with an Key Management Service (KMS) key (SSE-KMS), or a customer-provided encryption key (SSE-C), Amazon S3 uses the corresponding KMS key, or a customer-provided key to encrypt the uploaded parts. When you perform a CreateMultipartUpload operation, if you want to use a different type of encryption setting for the uploaded parts, you can request that Amazon S3 encrypts the object with a different encryption key (such as an Amazon S3 managed key, a KMS key, or a customer-provided key). When the encryption setting in your request is different from the default encryption configuration of the destination bucket, the encryption setting in your request takes precedence. If you choose to provide your own encryption key, the request headers you provide in UploadPart and UploadPartCopy requests must match the headers you used in the CreateMultipartUpload request.

    • Use KMS keys (SSE-KMS) that include the Amazon Web Services managed key (aws/s3) and KMS customer managed keys stored in Key Management Service (KMS) – If you want Amazon Web Services to manage the keys used to encrypt data, specify the following headers in the request.

      • x-amz-server-side-encryption

      • x-amz-server-side-encryption-aws-kms-key-id

      • x-amz-server-side-encryption-context

      • If you specify x-amz-server-side-encryption:aws:kms, but don't provide x-amz-server-side-encryption-aws-kms-key-id, Amazon S3 uses the Amazon Web Services managed key (aws/s3 key) in KMS to protect the data.

      • To perform a multipart upload with encryption by using an Amazon Web Services KMS key, the requester must have permission to the kms:Decrypt and kms:GenerateDataKey* actions on the key. These permissions are required because Amazon S3 must decrypt and read data from the encrypted file parts before it completes the multipart upload. For more information, see Multipart upload API and permissions and Protecting data using server-side encryption with Amazon Web Services KMS in the Amazon S3 User Guide.

      • If your Identity and Access Management (IAM) user or role is in the same Amazon Web Services account as the KMS key, then you must have these permissions on the key policy. If your IAM user or role is in a different account from the key, then you must have the permissions on both the key policy and your IAM user or role.

      • All GET and PUT requests for an object protected by KMS fail if you don't make them by using Secure Sockets Layer (SSL), Transport Layer Security (TLS), or Signature Version 4. For information about configuring any of the officially supported Amazon Web Services SDKs and Amazon Web Services CLI, see Specifying the Signature Version in Request Authentication in the Amazon S3 User Guide.

      For more information about server-side encryption with KMS keys (SSE-KMS), see Protecting Data Using Server-Side Encryption with KMS keys in the Amazon S3 User Guide.

    • Use customer-provided encryption keys (SSE-C) – If you want to manage your own encryption keys, provide all the following headers in the request.

      • x-amz-server-side-encryption-customer-algorithm

      • x-amz-server-side-encryption-customer-key

      • x-amz-server-side-encryption-customer-key-MD5

      For more information about server-side encryption with customer-provided encryption keys (SSE-C), see Protecting data using server-side encryption with customer-provided encryption keys (SSE-C) in the Amazon S3 User Guide.

  • Directory buckets -For directory buckets, only server-side encryption with Amazon S3 managed keys (SSE-S3) (AES256) is supported.

HTTP Host header syntax

Directory buckets - The HTTP Host header syntax is Bucket_name.s3express-az_id.region.amazonaws.com.

The following operations are related to CreateMultipartUpload:

Inheritance Hierarchy

System.Object
  Amazon.Runtime.AmazonWebServiceRequest
    Amazon.S3.Model.PutWithACLRequest
      Amazon.S3.Model.InitiateMultipartUploadRequest

Namespace: Amazon.S3.Model
Assembly: AWSSDK.S3.dll
Version: 3.x.y.z

Syntax

C# 
public class InitiateMultipartUploadRequest : PutWithACLRequest
         IAmazonWebServiceRequest

The InitiateMultipartUploadRequest type exposes the following members

Constructors

NameDescription
Public Method InitiateMultipartUploadRequest()

Properties

NameTypeDescription
Public Property BucketKeyEnabled System.Nullable<System.Boolean>

Gets and sets the property BucketKeyEnabled.

Specifies whether Amazon S3 should use an S3 Bucket Key for object encryption with server-side encryption using Key Management Service (KMS) keys (SSE-KMS).

General purpose buckets - Setting this header to true causes Amazon S3 to use an S3 Bucket Key for object encryption with SSE-KMS. Also, specifying this header with a PUT action doesn't affect bucket-level settings for S3 Bucket Key.

Directory buckets - S3 Bucket Keys are always enabled for GET and PUT operations in a directory bucket and can’t be disabled. S3 Bucket Keys aren't supported, when you copy SSE-KMS encrypted objects from general purpose buckets to directory buckets, from directory buckets to general purpose buckets, or between directory buckets, through CopyObject, UploadPartCopy, the Copy operation in Batch Operations, or the import jobs. In this case, Amazon S3 makes a call to KMS every time a copy request is made for a KMS-encrypted object.

Public Property BucketName System.String

Gets and sets the property BucketName.

The name of the bucket where the multipart upload is initiated and where the object is uploaded.

Directory buckets - When you use this operation with a directory bucket, you must use virtual-hosted-style requests in the format Bucket-name.s3express-zone-id.region-code.amazonaws.com. Path-style requests are not supported. Directory bucket names must be unique in the chosen Zone (Availability Zone or Local Zone). Bucket names must follow the format bucket-base-name--zone-id--x-s3 (for example, amzn-s3-demo-bucket--usw2-az1--x-s3). For information about bucket naming restrictions, see Directory bucket naming rules in the Amazon S3 User Guide.

Access points - When you use this action with an access point for general purpose buckets, you must provide the alias of the access point in place of the bucket name or specify the access point ARN. When you use this action with an access point for directory buckets, you must provide the access point name in place of the bucket name. When using the access point ARN, you must direct requests to the access point hostname. The access point hostname takes the form AccessPointName-AccountId.s3-accesspoint.Region.amazonaws.com. When using this action with an access point through the Amazon Web Services SDKs, you provide the access point ARN in place of the bucket name. For more information about access point ARNs, see Using access points in the Amazon S3 User Guide.

Object Lambda access points are not supported by directory buckets.

S3 on Outposts - When you use this action with S3 on Outposts, you must direct requests to the S3 on Outposts hostname. The S3 on Outposts hostname takes the form AccessPointName-AccountId.outpostID.s3-outposts.Region.amazonaws.com. When you use this action with S3 on Outposts, the destination bucket must be the Outposts access point ARN or the access point alias. For more information about S3 on Outposts, see What is S3 on Outposts? in the Amazon S3 User Guide.

Public Property CannedACL Amazon.S3.S3CannedACL

Gets and sets the property CannedACL.

The canned ACL to apply to the object. Amazon S3 supports a set of predefined ACLs, known as canned ACLs. Each canned ACL has a predefined set of grantees and permissions. For more information, see Canned ACL in the Amazon S3 User Guide.

By default, all objects are private. Only the owner has full access control. When uploading an object, you can grant access permissions to individual Amazon Web Services accounts or to predefined groups defined by Amazon S3. These permissions are then added to the access control list (ACL) on the new object. For more information, see Using ACLs. One way to grant the permissions using the request headers is to specify a canned ACL with the x-amz-acl request header.

  • This functionality is not supported for directory buckets.

  • This functionality is not supported for Amazon S3 on Outposts.

Public Property ChecksumAlgorithm Amazon.S3.ChecksumAlgorithm

Gets and sets the property ChecksumAlgorithm.

Indicates the algorithm that you want Amazon S3 to use to create the checksum for the object. For more information, see Checking object integrity in the Amazon S3 User Guide.

Public Property ChecksumType Amazon.S3.ChecksumType

Gets and sets the property ChecksumType.

Indicates the checksum type that you want Amazon S3 to use to calculate the object’s checksum value. For more information, see Checking object integrity in the Amazon S3 User Guide.

Public Property ContentType System.String

This is a convenience property for Headers.ContentType.

Public Property ExpectedBucketOwner System.String

Gets and sets the property ExpectedBucketOwner.

The account ID of the expected bucket owner. If the account ID that you provide does not match the actual owner of the bucket, the request fails with the HTTP status code 403 Forbidden (access denied).

Public Property Grants System.Collections.Generic.List<Amazon.S3.Model.S3Grant> Inherited from Amazon.S3.Model.PutWithACLRequest.
Public Property Headers Amazon.S3.Model.HeadersCollection

The collection of headers for the request.

Public Property Key System.String

Gets and sets the property Key.

Object key for which the multipart upload is to be initiated.

Public Property Metadata Amazon.S3.Model.MetadataCollection

The collection of meta data for the request.

Public Property ObjectLockLegalHoldStatus Amazon.S3.ObjectLockLegalHoldStatus

Gets and sets the property ObjectLockLegalHoldStatus.

Specifies whether you want to apply a legal hold to the uploaded object.

This functionality is not supported for directory buckets.

Public Property ObjectLockMode Amazon.S3.ObjectLockMode

Gets and sets the property ObjectLockMode.

Specifies the Object Lock mode that you want to apply to the uploaded object.

This functionality is not supported for directory buckets.

Public Property ObjectLockRetainUntilDate System.Nullable<System.DateTime>

Gets and sets the property ObjectLockRetainUntilDate.

Specifies the date and time when you want the Object Lock to expire.

This functionality is not supported for directory buckets.

Public Property RequestPayer Amazon.S3.RequestPayer

Gets and sets the property RequestPayer.

Public Property ServerSideEncryptionCustomerMethod Amazon.S3.ServerSideEncryptionCustomerMethod

Gets and sets the property ServerSideEncryptionCustomerMethod.

Specifies the algorithm to use when encrypting the object (for example, AES256).

This functionality is not supported for directory buckets.

Public Property ServerSideEncryptionCustomerProvidedKey System.String

Gets and sets the property ServerSideEncryptionCustomerProvidedKey.

Specifies the customer-provided encryption key for Amazon S3 to use in encrypting data. This value is used to store the object and then it is discarded; Amazon S3 does not store the encryption key. The key must be appropriate for use with the algorithm specified in the x-amz-server-side-encryption-customer-algorithm header.

This functionality is not supported for directory buckets.

Public Property ServerSideEncryptionCustomerProvidedKeyMD5 System.String

Gets and sets the property ServerSideEncryptionCustomerProvidedKeyMD5.

Specifies the 128-bit MD5 digest of the customer-provided encryption key according to RFC 1321. Amazon S3 uses this header for a message integrity check to ensure that the encryption key was transmitted without error.

This functionality is not supported for directory buckets.

Public Property ServerSideEncryptionKeyManagementServiceEncryptionContext System.String

Gets and sets the property ServerSideEncryptionKeyManagementServiceEncryptionContext.

Specifies the Amazon Web Services KMS Encryption Context to use for object encryption. The value of this header is a Base64 encoded string of a UTF-8 encoded JSON, which contains the encryption context as key-value pairs.

Directory buckets - You can optionally provide an explicit encryption context value. The value must match the default encryption context - the bucket Amazon Resource Name (ARN). An additional encryption context value is not supported.

Public Property ServerSideEncryptionKeyManagementServiceKeyId System.String

Gets and sets the property ServerSideEncryptionKeyManagementServiceKeyId.

Specifies the KMS key ID (Key ID, Key ARN, or Key Alias) to use for object encryption. If the KMS key doesn't exist in the same account that's issuing the command, you must use the full Key ARN not the Key ID.

General purpose buckets - If you specify x-amz-server-side-encryption with aws:kms or aws:kms:dsse, this header specifies the ID (Key ID, Key ARN, or Key Alias) of the KMS key to use. If you specify x-amz-server-side-encryption:aws:kms or x-amz-server-side-encryption:aws:kms:dsse, but do not provide x-amz-server-side-encryption-aws-kms-key-id, Amazon S3 uses the Amazon Web Services managed key (aws/s3) to protect the data.

Directory buckets - To encrypt data using SSE-KMS, it's recommended to specify the x-amz-server-side-encryption header to aws:kms. Then, the x-amz-server-side-encryption-aws-kms-key-id header implicitly uses the bucket's default KMS customer managed key ID. If you want to explicitly set the x-amz-server-side-encryption-aws-kms-key-id header, it must match the bucket's default customer managed key (using key ID or ARN, not alias). Your SSE-KMS configuration can only support 1 customer managed key per directory bucket's lifetime. The Amazon Web Services managed key (aws/s3) isn't supported. Incorrect key specification results in an HTTP 400 Bad Request error.

Public Property ServerSideEncryptionMethod Amazon.S3.ServerSideEncryptionMethod

Gets and sets the property ServerSideEncryptionMethod.

The server-side encryption algorithm used when you store this object in Amazon S3 or Amazon FSx.

  • Directory buckets - For directory buckets, there are only two supported options for server-side encryption: server-side encryption with Amazon S3 managed keys (SSE-S3) (AES256) and server-side encryption with KMS keys (SSE-KMS) (aws:kms). We recommend that the bucket's default encryption uses the desired encryption configuration and you don't override the bucket default encryption in your CreateSession requests or PUT object requests. Then, new objects are automatically encrypted with the desired encryption settings. For more information, see Protecting data with server-side encryption in the Amazon S3 User Guide. For more information about the encryption overriding behaviors in directory buckets, see Specifying server-side encryption with KMS for new object uploads.

    In the Zonal endpoint API calls (except CopyObject and UploadPartCopy) using the REST API, the encryption request headers must match the encryption settings that are specified in the CreateSession request. You can't override the values of the encryption settings (x-amz-server-side-encryption, x-amz-server-side-encryption-aws-kms-key-id, x-amz-server-side-encryption-context, and x-amz-server-side-encryption-bucket-key-enabled) that are specified in the CreateSession request. You don't need to explicitly specify these encryption settings values in Zonal endpoint API calls, and Amazon S3 will use the encryption settings values from the CreateSession request to protect new objects in the directory bucket.

    When you use the CLI or the Amazon Web Services SDKs, for CreateSession, the session token refreshes automatically to avoid service interruptions when a session expires. The CLI or the Amazon Web Services SDKs use the bucket's default encryption configuration for the CreateSession request. It's not supported to override the encryption settings values in the CreateSession request. So in the Zonal endpoint API calls (except CopyObject and UploadPartCopy), the encryption request headers must match the default encryption configuration of the directory bucket.

  • S3 access points for Amazon FSx - When accessing data stored in Amazon FSx file systems using S3 access points, the only valid server side encryption option is aws:fsx. All Amazon FSx file systems have encryption configured by default and are encrypted at rest. Data is automatically encrypted before being written to the file system, and automatically decrypted as it is read. These processes are handled transparently by Amazon FSx.

Public Property StorageClass Amazon.S3.S3StorageClass

Gets and sets the property StorageClass.

By default, Amazon S3 uses the STANDARD Storage Class to store newly created objects. The STANDARD storage class provides high durability and high availability. Depending on performance needs, you can specify a different Storage Class. For more information, see Storage Classes in the Amazon S3 User Guide.

  • Directory buckets only support EXPRESS_ONEZONE (the S3 Express One Zone storage class) in Availability Zones and ONEZONE_IA (the S3 One Zone-Infrequent Access storage class) in Dedicated Local Zones.

  • Amazon S3 on Outposts only uses the OUTPOSTS Storage Class.

Public Property TagSet System.Collections.Generic.List<Amazon.S3.Model.Tag>

Gets and sets the property TagSet.

The tag-set for the object. The tag-set must be encoded as URL Query parameters.

This functionality is not supported for directory buckets.

Starting with version 4 of the SDK this property will default to null. If no data for this property is returned from the service the property will also be null. This was changed to improve performance and allow the SDK and caller to distinguish between a property not set or a property being empty to clear out a value. To retain the previous SDK behavior set the AWSConfigs.InitializeCollections static property to true.

Public Property WebsiteRedirectLocation System.String

Gets and sets the property WebsiteRedirectLocation.

If the bucket is configured as a website, redirects requests for this object to another object in the same bucket or to an external URL. Amazon S3 stores the value of this header in the object metadata.

This functionality is not supported for directory buckets.

Examples

This example shows how to upload 13MB of data using mutlipart upload.
The data is contained in a stream and the upload is done in 3 parts: 5MB, 5MB, then the remainder.

Multipart Upload Sample


int MB = (int)Math.Pow(2, 20);

// Create a client
AmazonS3Client client = new AmazonS3Client();

// Define input stream
Stream inputStream = Create13MBDataStream();

// Initiate multipart upload
InitiateMultipartUploadRequest initRequest = new InitiateMultipartUploadRequest
{
    BucketName = "amzn-s3-demo-bucket",
    Key = "Item1"
};
InitiateMultipartUploadResponse initResponse = await client.InitiateMultipartUploadAsync(initRequest);

// Upload part 1
UploadPartRequest uploadRequest = new UploadPartRequest
{
    BucketName = "amzn-s3-demo-bucket",
    Key = "Item1",
    UploadId = initResponse.UploadId,
    PartNumber = 1,
    PartSize = 5 * MB,
    InputStream = inputStream
};
UploadPartResponse up1Response = await client.UploadPartAsync(uploadRequest);

// Upload part 2
uploadRequest = new UploadPartRequest
{
    BucketName = "amzn-s3-demo-bucket",
    Key = "Item1",
    UploadId = initResponse.UploadId,
    PartNumber = 2,
    PartSize = 5 * MB,
    InputStream = inputStream
};
UploadPartResponse up2Response = await client.UploadPartAsync(uploadRequest);

// Upload part 3
uploadRequest = new UploadPartRequest
{
    BucketName = "amzn-s3-demo-bucket",
    Key = "Item1",
    UploadId = initResponse.UploadId,
    PartNumber = 3,
    InputStream = inputStream
};
UploadPartResponse up3Response = await client.UploadPartAsync(uploadRequest);

// List parts for current upload
ListPartsRequest listPartRequest = new ListPartsRequest
{
    BucketName = "amzn-s3-demo-bucket",
    Key = "Item1",
    UploadId = initResponse.UploadId
};
ListPartsResponse listPartResponse = await client.ListPartsAsync(listPartRequest);
Debug.Assert(listPartResponse.Parts.Count == 3);

// Complete the multipart upload
CompleteMultipartUploadRequest compRequest = new CompleteMultipartUploadRequest
{
    BucketName = "amzn-s3-demo-bucket",
    Key = "Item1",
    UploadId = initResponse.UploadId,
    PartETags = new List<PartETag>
    {
        new PartETag { ETag = up1Response.ETag, PartNumber = 1 },
        new PartETag { ETag = up2Response.ETag, PartNumber = 2 },
        new PartETag { ETag = up3Response.ETag, PartNumber = 3 }
    }
};
CompleteMultipartUploadResponse compResponse = await client.CompleteMultipartUploadAsync(compRequest);

Version Information

.NET:
Supported in: 8.0 and newer, Core 3.1

.NET Standard:
Supported in: 2.0

.NET Framework:
Supported in: 4.7.2 and newer