Pascal (Lazarus/Delphi)

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>

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.AuthAws,
  Chilkat.Rest,
  Chilkat.Xml;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  xmlInit: TXml;
  uploadId: string;
  xmlPartsList: TXml;
  rest: TRest;
  bTls: Boolean;
  port: Integer;
  bAutoReconnect: Boolean;
  authAws: TAuthAws;
  responseXml: string;
  xml: TXml;

begin
  success := False;

  //  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.

  xmlInit := TXml.Create;
  success := xmlInit.LoadXmlFile('s3_multipart_uploads/initiate.xml');
  if (success <> True) then
    begin
      WriteLn('Did not find the initiate.xml XML file.');
      Exit;
    end;

  uploadId := xmlInit.GetChildContent('UploadId');
  WriteLn('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.)
  xmlPartsList := TXml.Create;
  success := xmlPartsList.LoadXmlFile('s3_multipart_uploads/partsList.xml');
  if (success <> True) then
    begin
      WriteLn('Did not find the partsList.xml XML file.');
      Exit;
    end;

  rest := TRest.Create;

  //  Connect to the Amazon AWS REST server.
  bTls := True;
  port := 443;
  bAutoReconnect := True;
  success := 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.
  authAws := TAuthAws.Create;
  authAws.AccessKey := 'AWS_ACCESS_KEY';
  authAws.SecretKey := 'AWS_SECRET_KEY';
  authAws.ServiceName := 's3';

  success := 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".
  responseXml := rest.FullRequestString('POST','/somethingBig.zip',xmlPartsList.GetXml());
  if (rest.LastMethodSuccess <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  When successful, the S3 Storage service will respond with a 200 response code,
  //  with an XML body.  
  if (rest.ResponseStatusCode <> 200) then
    begin
      //  Examine the request/response to see what happened.
      WriteLn('response status code = ' + rest.ResponseStatusCode);
      WriteLn('response status text = ' + rest.ResponseStatusText);
      WriteLn('response header: ' + rest.ResponseHeader);
      WriteLn('response body: ' + responseXml);
      WriteLn('---');
      WriteLn('LastRequestStartLine: ' + rest.LastRequestStartLine);
      WriteLn('LastRequestHeader: ' + rest.LastRequestHeader);
    end;

  //  Load the XML response into Chilkat XMl and emit via GetXml to see the XML in a pretty-printed (indented) readable format.
  xml := TXml.Create;
  xml.LoadXml(responseXml);
  WriteLn(xml.GetXml());
  WriteLn('----');

  WriteLn('Multipart upload completed.');


  xmlInit.Free;
  xmlPartsList.Free;
  rest.Free;
  authAws.Free;
  xml.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.