Dart

S3 Complete a Multipart Upload

See more Amazon S3 (new) Examples

This operation completes a multipart upload by assembling previously uploaded parts.

Processing of a Complete Multipart Upload request could take several minutes to complete. After Amazon S3 begins processing the request, it sends an HTTP response header that specifies a 200 OK response. While processing is in progress, Amazon S3 periodically sends whitespace characters to keep the connection from timing out. Because a request could fail after the initial 200 OK response has been sent, it is important that you check the response body to determine whether the request succeeded.

This example sends a POST request to complete a multipart upload, which looks like this:

POST /ObjectName?uploadId=UploadId HTTP/1.1
Host: BucketName.s3.amazonaws.com
Date: Date
Content-Length: Size
Authorization: authorization string

<CompleteMultipartUpload>
  <Part>
    <PartNumber>PartNumber</PartNumber>
    <ETag>ETag</ETag>
  </Part>
  ...
</CompleteMultipartUpload>

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // The 1st step in an S3 multipart upload is to initiate it,
  // as shown here: Initiate S3 Multipart Upload

  // The 2nd step is to upload the parts
  // as shown here: S3 Upload Parts

  // The 3rd and final step (this example) is to complete the multipart upload.

  // Other S3 Multipart Upload Examples:
  // Abort Multipart Upload
  // List Parts

  // When the multipart upload was initiated, an UploadId was provided in the XML response, and it 
  // was saved to a file.  Steps 2 and 3 begin by loading the XML and getting
  // the Upload ID.

  final xmlInit = CkXml();
  try {
    xmlInit.loadXmlFile('s3_multipart_uploads/initiate.xml');
  } on ChilkatException {
    print('Did not find the initiate.xml XML file.');
    return;
  }

  final uploadId = xmlInit.getChildContent('UploadId');
  print('UploadId = $uploadId');

  // We'll also need the XML file that contains a record of the parts
  // with part numbers and ETags.  (This file was produced when parts were being uploaded.)
  final xmlPartsList = CkXml();
  try {
    xmlPartsList.loadXmlFile('s3_multipart_uploads/partsList.xml');
  } on ChilkatException {
    print('Did not find the partsList.xml XML file.');
    return;
  }

  final rest = CkRest();

  // Connect to the Amazon AWS REST server.
  final bTls = true;
  final port = 443;
  final bAutoReconnect = true;
  rest.connect('s3.amazonaws.com', port, bTls, bAutoReconnect);

  // ----------------------------------------------------------------------------
  // Important: For buckets created in regions outside us-east-1,
  // there are three important changes that need to be made.
  // See Working with S3 Buckets in Non-us-east-1 Regions for the details.
  // ----------------------------------------------------------------------------

  // Provide AWS credentials for the REST call.
  final authAws = CkAuthAws();
  authAws.accessKey = 'AWS_ACCESS_KEY';
  authAws.secretKey = 'AWS_SECRET_KEY';
  authAws.serviceName = 's3';

  rest.setAuthAws(authAws);

  // Set the bucket name via the HOST header.
  // In this case, the bucket name is "chilkat100".
  rest.host = 'chilkat100.s3.amazonaws.com';

  // The "uploadId=UploadId" must be added as a query parameter.  This allows it to be 
  // incorporated into the AWS signature calculation, which is a requirement.
  // Therefore, we use AddQueryParam:
  rest.addQueryParam('uploadId', uploadId);

  // Our ObjectName in this case is "somethingBig.zip".
  final String responseXml;
  try {
    responseXml = rest.fullRequestString('POST', '/somethingBig.zip', xmlPartsList.getXml());
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // When successful, the S3 Storage service will respond with a 200 response code,
  // with an XML body.  
  if (rest.responseStatusCode != 200) {
    // Examine the request/response to see what happened.
    print('response status code = ${rest.responseStatusCode}');
    print('response status text = ${rest.responseStatusText}');
    print('response header: ${rest.responseHeader}');
    print('response body: $responseXml');
    print('---');
    print('LastRequestStartLine: ${rest.lastRequestStartLine}');
    print('LastRequestHeader: ${rest.lastRequestHeader}');
  }

  // Load the XML response into Chilkat XMl and emit via GetXml to see the XML in a pretty-printed (indented) readable format.
  final xml = CkXml();
  xml.loadXml(responseXml);
  print(xml.getXml());
  print('----');

  print('Multipart upload completed.');
}