(Delphi DLL) 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 non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Task, Http;

...

procedure TForm1.Button1Click(Sender: TObject);
var
http: HCkHttp;
task: HCkTask;
success: Boolean;
html: PWideChar;

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

http := CkHttp_Create();

task := CkHttp_QuickGetStrAsync(http,'https://www.chilkatsoft.com/helloWorld.html');
if (CkHttp_getLastMethodSuccess(http) = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;
// Start the background task.
success := CkTask_Run(task);
if (not success) then
  begin
    Memo1.Lines.Add(CkTask__lastErrorText(task));
    CkTask_Dispose(task);
    Exit;
  end;

// The application is now free to do anything else
// while the email is being sent.

// For this example, we'll simply sleep and periodically
// check to see if the HTTPS GET if finished.
while CkTask_getFinished(task) <> True do
  begin
    // Sleep 100 ms.
    CkTask_SleepMs(task,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 (CkTask_getStatusInt(task) <> 7) then
  begin
    Memo1.Lines.Add('Task did not complete.');
    Memo1.Lines.Add('task status: ' + CkTask__status(task));
    CkTask_Dispose(task);
    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 := CkTask__getResultString(task);

Memo1.Lines.Add(html);

CkTask_Dispose(task);

CkHttp_Dispose(http);

end;