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(Delphi ActiveX) Async Task Chain (another example)Demonstrates using a task chain to run a sequence of FTP tasks asynchronously.
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 chilkatGlob: TChilkatGlobal; success: Integer; ftp: TChilkatFtp2; taskChain: TChilkatTaskChain; task: IChilkatTask; localFilename: WideString; remoteFilename: WideString; numTasks: Integer; taskIdx: Integer; 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 := TChilkatGlobal.Create(Self); success := chilkatGlob.UnlockBundle('Anything for 30-day trial.'); if (success <> 1) then begin Memo1.Lines.Add(chilkatGlob.LastErrorText); Exit; end; ftp := TChilkatFtp2.Create(Self); ftp.Hostname := 'ftp.example.com'; ftp.Username := 'login'; ftp.Password := 'password'; // Connect and login to the FTP server. success := ftp.Connect(); if (success <> 1) then begin Memo1.Lines.Add(ftp.LastErrorText); Exit; end; taskChain := TChilkatTaskChain.Create(Self); // Create a task to change to the remote directory where the file will be uploaded. task := ftp.ChangeRemoteDirAsync('junk'); if (ftp.LastMethodSuccess = 0) then begin Memo1.Lines.Add(ftp.LastErrorText); Exit; end; // Add this task to the task chain. success := taskChain.Append(task); // Create a task to upload a file. localFilename := 'c:/temp/hamlet.xml'; remoteFilename := 'hamlet.xml'; task := ftp.PutFileAsync(localFilename,remoteFilename); if (ftp.LastMethodSuccess = 0) then begin Memo1.Lines.Add(ftp.LastErrorText); Exit; end; // Add this task to the task chain. success := taskChain.Append(task); // Start the task chain running in a background thread. // Each task is run one after the other (on the same background thread) until all tasks have completed. // The task chain will stop at the first task that fails. taskChain.StopOnFailedTask := 1; success := taskChain.Run(); if (not success) then begin Memo1.Lines.Add(taskChain.LastErrorText); Exit; end; // The application is now free to do anything else // while the FTP commands are being run... // For this example, we'll simply sleep and periodically // check to see if the taskchain if finished. while taskChain.Finished <> 1 do begin // Sleep 100 ms. taskChain.SleepMs(100); end; // A finished task chain could be one that was canceled, aborted, or truly finished. // If the task chain "completed", then it ran to completion. 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 (taskChain.StatusInt <> 7) then begin Memo1.Lines.Add('Task did not complete.'); Memo1.Lines.Add('task chain status: ' + taskChain.Status); Exit; end; // If we got to this point, the ChangeRemoteDir and PutFile were successful. // We can visually verify by examining the LastErrorText that was recorded for each // of these method calls.. numTasks := taskChain.NumTasks; taskIdx := 0; while (taskIdx < numTasks) do begin task := taskChain.GetTask(taskIdx); // Examine the status of this task, and the ResultErrorText // (the ResultErrorText is the ftp.LastErrorText captured for FTP method called by the task). // Everything should indicate success. Memo1.Lines.Add('task status: ' + task.Status); Memo1.Lines.Add('task log: ' + task.ResultErrorText); taskIdx := taskIdx + 1; end; success := ftp.Disconnect(); end; |
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