(Delphi DLL) Async SFTP Progress Info

Demonstrates checking for progress info updates when running a task asynchronously. This example demonstrates an SFTP download.

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, Global, Task, SFtp;

...

procedure TForm1.Button1Click(Sender: TObject);
var
chilkatGlob: HCkGlobal;
success: Boolean;
sftp: HCkSFtp;
hostname: PWideChar;
port: Integer;
localFilePath: PWideChar;
remoteFilePath: PWideChar;
task: HCkTask;
curPctDone: Integer;
name: PWideChar;
value: PWideChar;

begin
// All Chilkat classes can be unlocked at once at the beginning of a program
// by calling UnlockBundle.  It requires a Bundle unlock code.
chilkatGlob := CkGlobal_Create();
success := CkGlobal_UnlockBundle(chilkatGlob,'Anything for 30-day trial.');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkGlobal__lastErrorText(chilkatGlob));
    Exit;
  end;

sftp := CkSFtp_Create();

// Set some timeouts, in milliseconds:
CkSFtp_putConnectTimeoutMs(sftp,15000);
CkSFtp_putIdleTimeoutMs(sftp,15000);

// Connect to the SSH server.  
// The standard SSH port = 22
// The hostname may be a hostname or IP address.
hostname := 'www.my-ssh-server.com';
port := 22;
success := CkSFtp_Connect(sftp,hostname,port);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

// Authenticate with the SSH server.  Chilkat SFTP supports
// both password-based authenication as well as public-key
// authentication.  This example uses password authenication.
success := CkSFtp_AuthenticatePw(sftp,'myLogin','myPassword');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

// After authenticating, the SFTP subsystem must be initialized:
success := CkSFtp_InitializeSftp(sftp);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

// --------------------
// Download a file
// --------------------
localFilePath := 'c:/temp/hamlet.xml';
remoteFilePath := 'subdir1/subdir2/hamlet.xml';

// Call the async version of the DownloadFileByName method to return a task object.
// The task object is loaded, but is in the Inert state -- meaning it is
// not yet scheduled to run on Chilkat's background thread pool.
task := CkSFtp_DownloadFileByNameAsync(sftp,remoteFilePath,localFilePath);
if (CkSFtp_getLastMethodSuccess(sftp) = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

// Before starting the task, tell it to keep an in-memory log of what would've been
// ProgressInfo callbacks.
CkTask_putKeepProgressLog(task,True);

// Schedule the task for running on the thread pool.  This changes the task's state
// from Inert to Live.
success := CkTask_Run(task);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkTask__lastErrorText(task));
    CkTask_Dispose(task);
    Exit;
  end;

// The application is now free to do anything else
// while the file is being downloaded.

// For this example, we'll simply sleep and periodically
// check to see if the download is finished, and report the progress
// along the way.
curPctDone := 0;

while CkTask_getFinished(task) <> True do
  begin

    if (CkTask_getPercentDone(task) <> curPctDone) then
      begin
        curPctDone := CkTask_getPercentDone(task);
        Memo1.Lines.Add(IntToStr(curPctDone) + ' percent done');
      end;

    // Check the progress info log.
    // Emit any log entries..
    while (CkTask_getProgressLogSize(task) > 0) do
      begin
        // Get the 1st entry, emit it, and then remove it..
        name := CkTask__progressInfoName(task,0);
        value := CkTask__progressInfoValue(task,0);

        // Entries reporting the received byte count will have the name "RcvByteCount"
        // Entries reporting the current bytes-per-second will have the name "RcvBytesPerSec"

        Memo1.Lines.Add(name + ': ' + value);
        CkTask_RemoveProgressInfo(task,0);
      end;

    // Sleep 100 ms.
    CkTask_SleepMs(task,100);

  end;

// Just in case there are any remaining entries...
while (CkTask_getProgressLogSize(task) > 0) do
  begin
    // Get the 1st entry, emit it, and then remove it..
    name := CkTask__progressInfoName(task,0);
    value := CkTask__progressInfoValue(task,0);
    Memo1.Lines.Add(name + ': ' + value);
    CkTask_RemoveProgressInfo(task,0);
  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 DownloadFileByName method returns a boolean.  Therefore, after the task is finished,
// we can get the boolean result by calling GetResultBool.  This is the return value had
// we called DownloadFileByName synchronously.
success := CkTask_GetResultBool(task);
if (success <> True) then
  begin
    // The task's ResultErrorText contains what would have been in the LastErrorText property had
    // the DownloadFileByName method been called synchronously.
    Memo1.Lines.Add(CkTask__resultErrorText(task));
  end
else
  begin
    Memo1.Lines.Add('File downloaded asynchronously.');
  end;

CkTask_Dispose(task);

CkGlobal_Dispose(chilkatGlob);
CkSFtp_Dispose(sftp);

end;