Delphi ActiveX

REST Stream Response to File (Streaming Download) (Amazon S3)

See more Amazon S3 (new) Examples

Demonstrates how to stream the response body directly to a file. (The example shows how to stream a JPG from the Amazon S3 service.) Delphi ActiveX

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
success: Integer;
rest: TChilkatRest;
bTls: Integer;
port: Integer;
bAutoReconnect: Integer;
authAws: TChilkatAuthAws;
responseStatusCode: Integer;
bodyStream: TChilkatStream;
errResponse: WideString;

begin
success := 0;

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

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';

// Send the request to download the JPG.
success := rest.SendReqNoBody('GET','/starfish.jpg');
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// Read the response header.
responseStatusCode := rest.ReadResponseHeader();
if (responseStatusCode < 0) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Response status code = ' + IntToStr(responseStatusCode));

// We expect a 200 response status if the JPG data is coming.
// Otherwise, we'll get a string response body with an error message(or no response body).
if (responseStatusCode = 200) then
  begin

    bodyStream := TChilkatStream.Create(Self);

    // The stream's sink will be a file.
    bodyStream.SinkFile := 'qa_output/starfish.jpg';

    // Read the response body to the stream.  Given that we've
    // set the stream's sink to a file, it will stream directly
    // to the file.
    success := rest.ReadRespBodyStream(bodyStream.ControlInterface,1);
    if (success <> 1) then
      begin
        Memo1.Lines.Add(rest.LastErrorText);
        Exit;
      end;

    Memo1.Lines.Add('Successfully received the JPG file.');

  end
else
  begin
    errResponse := rest.ReadRespBodyString();
    if (rest.LastMethodSuccess <> 1) then
      begin
        Memo1.Lines.Add(rest.LastErrorText);
      end
    else
      begin
        Memo1.Lines.Add(errResponse);
      end;
  end;
end;