Asynchronous FTP Download

The Chilkat FTP component supports asynchronous uploads and downloads. This examples demonstrates doing a download in a background thread. The download is started by calling AsyncGetFileStart. While the download is in progress, your program may do other tasks. You may periodically check the AsyncFinished property to determine when the transfer is finished. The example below provides the remainder of the details.

Download Chilkat FTP2 ActiveX

uses
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, StdCtrls,
    CHILKATFTP2Lib_TLB,
    OleCtrls;

...

procedure TForm1.Button1Click(Sender: TObject);
var
ftp: TChilkatFtp2;
success: Integer;
localFilename: String;
remoteFilename: String;

begin
ftp := TChilkatFtp2.Create(Self);

//  Any string unlocks the component for the 1st 30-days.
success := ftp.UnlockComponent('Anything for 30-day trial');
if (success <> 1) then
  begin
    ShowMessage(ftp.LastErrorText);

  end;

ftp.Hostname := 'www.secureftp-test.com';
ftp.Username := 'test';
ftp.Password := 'test';

//  Connect and login to the FTP server.
success := ftp.Connect();
if (success <> 1) then
  begin
    ShowMessage(ftp.LastErrorText);

  end;

localFilename := 'hamlet.xml';
remoteFilename := 'hamlet.xml';

//  Begin the download in a background thread.
//  Only 1 background upload or download may be active at any time.
//  (per instance of an FTP object)
success := ftp.AsyncGetFileStart(remoteFilename,localFilename);
if (success <> 1) then
  begin
    ShowMessage(ftp.LastErrorText);

  end;

//  The application is now free to do anything else
//  while the file is downloading.
//  For this example, we'll simply sleep and periodically
//  check to see if the transfer if finished.  While checking
//  however, we'll report on the progress in both number
//  of bytes tranferred and performance in bytes/second.
while ftp.AsyncFinished <> 1 do
  begin

    Memo1.Lines.Add(IntToStr(ftp.AsyncBytesReceived)
         + ' bytes received');
    Memo1.Lines.Add(IntToStr(ftp.DownloadRate)
         + ' bytes per second');

    //  Sleep 1 second.
    ftp.SleepMs(1000);

  end;

//  Did the download succeed?
if (ftp.AsyncSuccess = 1) then
  begin
    ShowMessage('File Downloaded!');
  end
else
  begin
    //  The error information for asynchronous ops
    //  is in AsyncLog as opposed to LastErrorText
    ShowMessage(ftp.AsyncLog);
  end;

ftp.Disconnect();
end;