Lazarus Pascal

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. Lazarus Pascal

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.