(Delphi ActiveX) Async Methods Returning an String

Demonstrates how to call an asynchronous method that returns a string. This example sends an HTTPS GET request to a URL and gets the HTML response.

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
http: TChilkatHttp;
task: IChilkatTask;
success: Integer;
html: WideString;

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

http := TChilkatHttp.Create(Self);

task := http.QuickGetStrAsync('https://www.chilkatsoft.com/helloWorld.html');
if (http.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(http.LastErrorText);
    Exit;
  end;
// Start the background task.
success := task.Run();
if (not success) then
  begin
    Memo1.Lines.Add(task.LastErrorText);

    Exit;
  end;

// The application is now free to do anything else

// For this example, we'll simply sleep and periodically
// check to see if the HTTPS GET if finished.
while task.Finished <> 1 do
  begin
    // Sleep 100 ms.
    task.SleepMs(100);
  end;

// A finished task could be one that was canceled, aborted, or truly finished.  

// If the task was "canceled", it was canceled prior to actually starting.  This could
// happen if the task was canceled while waiting in a thread pool queue to be scheduled by Chilkat's
// background thread pool scheduler.  

// If the task was "aborted", it indicates that it was canceled while running in a background thread.  
// The ResultErrorText will likely indicate that the task was aborted.

// If the task "completed", then it ran to completion, but the actual success/failure of the method
// is determined by the result obtained via a GetResult* method.  (A "completed" task will
// have a StatusInt equal to 7.   If the task finished, but was not completed, then it must've
// been aborted or canceled:
if (task.StatusInt <> 7) then
  begin
    Memo1.Lines.Add('Task did not complete.');
    Memo1.Lines.Add('task status: ' + task.Status);

    Exit;
  end;

// The QuickGetStr method returns a string.  Therefore, after the task is finished,
// we can get the string result by calling GetResultString.  This is the return value had
// we called QuickGetStr synchronously.
html := task.GetResultString();

Memo1.Lines.Add(html);
end;