Pascal (Lazarus/Delphi)

REST Asynchronous Streaming Upload File

See more REST Examples

Demonstrates how to asynchronous streaming upload a file to cloud storage. This particular example demonstrates an upload to the Azure Cloud Storage service. The same concepts apply to S3, Google Cloud, and Google Drive. 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.Rest,
  Chilkat.AuthAzureStorage,
  Chilkat.Task,
  Chilkat.Stream;

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

procedure RunDemo;
var
  success: Boolean;
  rest: TRest;
  bTls: Boolean;
  port: Integer;
  bAutoReconnect: Boolean;
  azAuth: TAuthAzureStorage;
  sendStream: TStream;
  task: TTask;
  curPctDone: Integer;
  responseStatusCode: Integer;
  responseBodyStr: 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 Azure Storage Blob Service
  bTls := True;
  port := 443;
  bAutoReconnect := True;
  //  In this example, the storage account name is "chilkat".
  success := rest.Connect('chilkat.blob.core.windows.net',port,bTls,bAutoReconnect);
  if (success <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  Provide Azure Cloud credentials for the REST call.
  azAuth := TAuthAzureStorage.Create;
  azAuth.AccessKey := 'AZURE_ACCESS_KEY';
  //  The account name used here should match the 1st part of the domain passed in the call to Connect (above).
  azAuth.Account := 'chilkat';
  azAuth.Scheme := 'SharedKey';
  azAuth.Service := 'Blob';
  //  This causes the "x-ms-version: 2021-08-06" header to be automatically added.
  azAuth.XMsVersion := '2021-08-06';
  success := rest.SetAuthAzureStorage(azAuth);

  //  Set some request headers.
  success := rest.AddHeader('x-ms-blob-content-disposition','attachment; filename="thisIsATest.txt"');
  success := rest.AddHeader('x-ms-blob-type','BlockBlob');
  success := rest.AddHeader('x-ms-meta-m1','v1');
  success := rest.AddHeader('x-ms-meta-m2','v2');

  //  Note: The application does not need to explicitly set the following
  //  headers: x-ms-date, Authorization, and Content-Length.  These headers
  //  are automatically set by Chilkat.

  sendStream := TStream.Create;

  //  Define the source data for the stream to be a file.
  sendStream.SourceFile := 'qa_data/hamlet.xml';

  //  Create a background thread task to upload from the stream
  //  The name of the Azure storage container is "test".
  task := rest.FullRequestStreamAsync('PUT','/test/thisIsATest.txt',sendStream);

  //  Start the task. 
  success := task.Run();

  //  In this example, we'll simply sleep and periodically
  //  check to see if the REST upload if finished.
  curPctDone := 0;
  while task.Finished <> True do
    begin
      task.SleepMs(100);
    end;

  //  Check to see if the call to FullRequestStream in the background thread pool succeeded.
  if (task.TaskSuccess <> True) then
    begin
      //  Show what would've been the LastErrorText had FullRequestStream been called synchronously
      WriteLn(task.ResultErrorText);
      task.Free;
      Exit;
    end;

  responseStatusCode := rest.ResponseStatusCode;

  //  When successful, the Azure Storage service will respond with a 201 response code,
  //  with an empty body.  Therefore, in the success condition, the responseStr is empty.
  if (responseStatusCode = 201) then
    begin
      WriteLn('File uploaded.');
    end
  else
    begin
      //  It failed, so examine the response body, if one was returned:
      //  Given that FullRequestStream returns a string, the return value is obtained via GetResultString.
      responseBodyStr := task.GetResultString();
      WriteLn('response body (if any): ' + responseBodyStr);

      //  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('---');
      WriteLn('LastRequestStartLine: ' + rest.LastRequestStartLine);
      WriteLn('LastRequestHeader: ' + rest.LastRequestHeader);
    end;

  task.Free;


  rest.Free;
  azAuth.Free;
  sendStream.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.