Pascal (Lazarus/Delphi)

(using AWS Signature Version 2) Streaming Download to File

See more Amazon S3 (new) Examples

The main purpose of this example is to demonstrate how to use the older Signature Version 2 authentication w/ S3. It uses V2 authentication to download a file. 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.Stream;

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

procedure RunDemo;
var
  success: Boolean;
  rest: TRest;
  bTls: Boolean;
  port: Integer;
  bAutoReconnect: Boolean;
  authAws: TAuthAws;
  responseStatusCode: Integer;
  bodyStream: TStream;
  errResponse: string;

begin
  success := False;

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

  rest := TRest.Create;

  //  Connect to the Amazon AWS REST server.
  bTls := True;
  port := 443;
  bAutoReconnect := True;
  //  The file is located in the bucket named "chilkat100", which becomes part of the domain:
  success := rest.Connect('chilkat100.s3.amazonaws.com',port,bTls,bAutoReconnect);

  //  Provide AWS credentials for the REST call.
  authAws := TAuthAws.Create;
  authAws.AccessKey := 'AWS_ACCESS_KEY';
  authAws.SecretKey := 'AWS_SECRET_KEY';
  authAws.ServiceName := 's3';

  //  For AWS Signature Version 2, the following two properties need to be set:
  authAws.SignatureVersion := 2;
  //  See http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#ConstructingTheCanonicalizedResourceElement
  authAws.CanonicalizedResourceV2 := '/chilkat100/starfish.jpg';

  success := rest.SetAuthAws(authAws);

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

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

  WriteLn('Response status code = ' + 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 := TStream.Create;

      //  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,True);
      if (success <> True) then
        begin
          WriteLn(rest.LastErrorText);
          Exit;
        end;

      WriteLn('Successfully received the JPG file.');

    end
  else
    begin
      errResponse := rest.ReadRespBodyString();
      if (rest.LastMethodSuccess <> True) then
        begin
          WriteLn(rest.LastErrorText);
        end
      else
        begin
          WriteLn(errResponse);
        end;
    end;


  rest.Free;
  authAws.Free;
      bodyStream.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.