(Delphi ActiveX) S3 Upload the Parts for a Multipart Upload

This example uploads a large file in parts. The multipart upload needs to have been first initiated prior to uploading the parts.

See http://docs.aws.amazon.com/AmazonS3/latest/API/mpUploadUploadPart.html for more information about uploading parts.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
xmlInit: TChilkatXml;
success: Integer;
uploadId: WideString;
fileToUploadPath: WideString;
partSize: Integer;
fac: TCkFileAccess;
numParts: Integer;
partsListFile: WideString;
partsListXml: TChilkatXml;
rest: TChilkatRest;
bTls: Integer;
port: Integer;
bAutoReconnect: Integer;
authAws: TChilkatAuthAws;
partNumber: Integer;
sbPartNumber: TChilkatStringBuilder;
bPartAlreadyUploaded: Integer;
numUploadedParts: Integer;
xRec0: IChilkatXml;
foundRec: IChilkatXml;
fileStream: TChilkatStream;
responseStr: WideString;
etag: WideString;
xPart: IChilkatXml;

begin
// In the 1st step for uploading a large file, the multipart upload was initiated
// as shown here: Initiate Multipart Upload

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

// When we initiated the multipart upload, we saved the XML response to a file.  This
// XML response contains the UploadId.  We'll begin by loading that XML and getting
// the Upload ID.

xmlInit := TChilkatXml.Create(Self);
success := xmlInit.LoadXmlFile('s3_multipart_uploads/initiate.xml');
if (success <> 1) then
  begin
    Memo1.Lines.Add('Did not find the initiate.xml XML file.');
    Exit;
  end;

uploadId := xmlInit.GetChildContent('UploadId');
Memo1.Lines.Add('UploadId = ' + uploadId);

// When uploading parts, we need to keep an XML record of each part number
// and its corresponding ETag, which is received in the response for each part.
// There can be up to 10000 parts, numbered 1 to 10000.  
// After all parts have been uploaded, the final step will be to complete
// the multipart upload (see Complete Multipart Upload)

// In this example, the large file we want to upload is somethingBig.zip
fileToUploadPath := 's3_multipart_uploads/somethingBig.zip';

// The minimum allowed part size is 5MB (5242880 bytes).  The last part can be smaller because
// it will contain the remainder of the file.  (This minimum is enforced by the AWS service.)
// We'll use the minimum allowed part size for this example.
partSize := 5242880;

// Let's use Chilkat's FileAccess API to examine the file to be uploaded.  We'll get the size
// of the file and find out how many parts will be needed, including the final "partial" part.
fac := TCkFileAccess.Create(Self);
fac.OpenForRead(fileToUploadPath);

// How many parts will there be if each part is 5242880 bytes?
numParts := fac.GetNumBlocks(partSize);
Memo1.Lines.Add('numParts = ' + IntToStr(numParts));
fac.FileClose();

// Imagine that we may be running this for the 1st time, or maybe we already
// attempted to upload parts, and something failed. Maybe there was a network problem
// the resulted in not all parts getting uploaded.  We'll write this code so that if run again,
// it will upload whatever parts haven't yet been uploaded.

// We'll keep a partsList.xml file to record the parts that have already been successfully
// uploaded.  If this file does not yet exist, we'll create it..
partsListFile := 's3_multipart_uploads/partsList.xml';
partsListXml := TChilkatXml.Create(Self);
if (fac.FileExists(partsListFile) = 1) then
  begin
    partsListXml.LoadXmlFile(partsListFile);
  end;
// Make sure the top-level tag is "CompleteMultipartUpload"
partsListXml.Tag := 'CompleteMultipartUpload';

// --------------------------------------
// Before entering the loop to upload parts,
// setup the REST object with AWS authentication,
// and make the initial connection.
rest := TChilkatRest.Create(Self);

// Connect to the Amazon AWS REST server.
bTls := 1;
port := 443;
bAutoReconnect := 1;
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 := TChilkatAuthAws.Create(Self);
authAws.AccessKey := 'AWS_ACCESS_KEY';
authAws.SecretKey := 'AWS_SECRET_KEY';
authAws.ServiceName := 's3';
success := rest.SetAuthAws(authAws.ControlInterface);

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

partNumber := 1;
sbPartNumber := TChilkatStringBuilder.Create(Self);

while (partNumber <= numParts) do
  begin
    Memo1.Lines.Add('---- ' + IntToStr(partNumber) + ' ----');

    // This cumbersome way of converting an integer to a string is because
    // Chilkat examples are written in a script that is converted to many programming languages.
    // At this time, the translator does not have integer-to-string code generation capability..
    sbPartNumber.Clear();
    sbPartNumber.AppendInt(partNumber);

    bPartAlreadyUploaded := 0;

    // If there are no children, then the XML is empty and no parts have yet been uploaded.
    numUploadedParts := partsListXml.NumChildren;
    if (numUploadedParts > 0) then
      begin
        // If some parts have been uploaded, check to see if this particular part was already upload.
        // If so, then it can be skipped.

        // Position ourselves at the 1st record.
        xRec0 := partsListXml.GetChild(0);
        foundRec := xRec0.FindNextRecord('PartNumber',sbPartNumber.GetAsString());
        if (xRec0.LastMethodSuccess = 1) then
          begin
            bPartAlreadyUploaded := 1;
            Memo1.Lines.Add('Part ' + IntToStr(partNumber) + ' was previously uploaded.');
            Memo1.Lines.Add(foundRec.GetXml());

          end;

      end;

    // If this part was not already uploaded, we need to upload.
    // Also update the partsListXml and save as each part is successfully uploaded.
    if (bPartAlreadyUploaded = 0) then
      begin
        Memo1.Lines.Add('Uploading part ' + IntToStr(partNumber) + ' ...');

        // Setup the stream source for the large file to be uploaded..
        fileStream := TChilkatStream.Create(Self);
        fileStream.SourceFile := fileToUploadPath;
        // The Chilkat Stream API has features to make uploading a parts
        // of a file easy.  Indicate the part size by setting the SourceFilePartSize
        // property.
        fileStream.SourceFilePartSize := partSize;

        // Our HTTP start line to upload a part will look like this:
        // PUT /ObjectName?partNumber=PartNumber&uploadId=UploadId HTTP/1.1

        // Set the query params.  We'll need partNumber and uploadId.
        // Make sure the query params from previous iterations are clear.
        rest.ClearAllQueryParams();
        rest.AddQueryParam('partNumber',sbPartNumber.GetAsString());
        rest.AddQueryParam('uploadId',uploadId);

        // Upload this particular file part.
        // Tell the fileStream which part is being uploaded.
        // Our partNumber is 1-based (the 1st part is at index 1), but the fileStream's SourceFilePart
        // property is 0-based.  Therefore we use partNumber-1.
        fileStream.SourceFilePart := partNumber - 1;

        // Because the SourceFilePart and SourceFilePartSize properties are set, the stream will 
        // will provide just that part of the file.  
        responseStr := rest.FullRequestStream('PUT','/somethingBig.zip',fileStream.ControlInterface);
        if (rest.LastMethodSuccess <> 1) then
          begin
            Memo1.Lines.Add(rest.LastErrorText);
            Exit;
          end;

        if (rest.ResponseStatusCode <> 200) then
          begin
            // Examine the request/response to see what happened.
            Memo1.Lines.Add('response status code = ' + IntToStr(rest.ResponseStatusCode));
            Memo1.Lines.Add('response status text = ' + rest.ResponseStatusText);
            Memo1.Lines.Add('response header: ' + rest.ResponseHeader);
            Memo1.Lines.Add('response body: ' + responseStr);
            Memo1.Lines.Add('---');
            Memo1.Lines.Add('LastRequestStartLine: ' + rest.LastRequestStartLine);
            Memo1.Lines.Add('LastRequestHeader: ' + rest.LastRequestHeader);
            Exit;
          end;

        // OK, this part was uploaded..
        // The response will have a 0-length body.  The only information we need is the 
        // ETag response header field.
        etag := rest.ResponseHdrByName('ETag');
        // It should be present, but just in case there was no ETag header...
        if (rest.LastMethodSuccess <> 1) then
          begin
            Memo1.Lines.Add('No ETag response header found!');
            Memo1.Lines.Add('response header: ' + rest.ResponseHeader);
            Exit;
          end;

        // We need to add record to the partsListXml.
        // The record will look like this:
        // &lt;Part>
        //   &lt;PartNumber>PartNumber&lt;/PartNumber>
        //   &lt;ETag>ETag&lt;/ETag>
        // &lt;/Part>
        xPart := partsListXml.NewChild('Part','');
        xPart.NewChildInt2('PartNumber',partNumber);
        xPart.NewChild2('ETag',etag);

        success := partsListXml.SaveXml(partsListFile);
        if (success <> 1) then
          begin
            Memo1.Lines.Add(partsListXml.LastErrorText);
            Exit;
          end;

        Memo1.Lines.Add('-- Part ' + IntToStr(partNumber) + ' uploaded. ---------------------');
      end;

    partNumber := partNumber + 1;
  end;

Memo1.Lines.Add('Finished.  All parts uploaded.');
end;