(Delphi ActiveX) REST Asynchronous Streaming Upload File

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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.

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
rest: TChilkatRest;
bTls: Integer;
port: Integer;
bAutoReconnect: Integer;
success: Integer;
azAuth: TChilkatAuthAzureStorage;
sendStream: TChilkatStream;
task: IChilkatTask;
curPctDone: Integer;
responseStatusCode: Integer;
responseBodyStr: WideString;

begin
// 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 Azure Storage Blob Service
bTls := 1;
port := 443;
bAutoReconnect := 1;
// In this example, the storage account name is "chilkat".
success := rest.Connect('chilkat.blob.core.windows.net',port,bTls,bAutoReconnect);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

// Provide Azure Cloud credentials for the REST call.
azAuth := TChilkatAuthAzureStorage.Create(Self);
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.ControlInterface);

// 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 := TChilkatStream.Create(Self);

// 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.ControlInterface);

// 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 <> 1 do
  begin
    task.SleepMs(100);
  end;

// Check to see if the call to FullRequestStream in the background thread pool succeeded.
if (task.TaskSuccess <> 1) then
  begin
    // Show what would've been the LastErrorText had FullRequestStream been called synchronously
    Memo1.Lines.Add(task.ResultErrorText);

    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
    Memo1.Lines.Add('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();
    Memo1.Lines.Add('response body (if any): ' + responseBodyStr);

    // 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('---');
    Memo1.Lines.Add('LastRequestStartLine: ' + rest.LastRequestStartLine);
    Memo1.Lines.Add('LastRequestHeader: ' + rest.LastRequestHeader);
  end;
end;