(Lianja) Async Task Chain (another example)

Demonstrates using a task chain to run a sequence of FTP tasks asynchronously.

Chilkat Lianja Extension Download Chilkat Lianja Extension

// All Chilkat classes can be unlocked at once at the beginning of a program
// by calling UnlockBundle.  It requires a Bundle unlock code.
loChilkatGlob = createobject("CkGlobal")
llSuccess = loChilkatGlob.UnlockBundle("Anything for 30-day trial.")
if (llSuccess <> .T.) then
    ? loChilkatGlob.LastErrorText
    release loChilkatGlob
    return
endif

loFtp = createobject("CkFtp2")

loFtp.Hostname = "ftp.example.com"
loFtp.Username = "login"
loFtp.Password = "password"

// Connect and login to the FTP server.
llSuccess = loFtp.Connect()
if (llSuccess <> .T.) then
    ? loFtp.LastErrorText
    release loChilkatGlob
    release loFtp
    return
endif

loTaskChain = createobject("CkTaskChain")

// Create a task to change to the remote directory where the file will be uploaded.
loTask = loFtp.ChangeRemoteDirAsync("junk")
if (loFtp.LastMethodSuccess = .F.) then
    ? loFtp.LastErrorText
    release loChilkatGlob
    release loFtp
    release loTaskChain
    return
endif

// Add this task to the task chain.
llSuccess = loTaskChain.Append(loTask)
release loTask

// Create a task to upload a file.
lcLocalFilename = "c:/temp/hamlet.xml"
lcRemoteFilename = "hamlet.xml"

loTask = loFtp.PutFileAsync(lcLocalFilename,lcRemoteFilename)
if (loFtp.LastMethodSuccess = .F.) then
    ? loFtp.LastErrorText
    release loChilkatGlob
    release loFtp
    release loTaskChain
    return
endif

// Add this task to the task chain.
llSuccess = loTaskChain.Append(loTask)
release loTask

// 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.
loTaskChain.StopOnFailedTask = .T.
llSuccess = loTaskChain.Run()
if (not llSuccess) then
    ? loTaskChain.LastErrorText
    release loChilkatGlob
    release loFtp
    release loTaskChain
    return
endif

// 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. 
do while loTaskChain.Finished <> .T.

    // Sleep 100 ms.
    loTaskChain.SleepMs(100)

enddo

// 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 (loTaskChain.StatusInt <> 7) then
    ? "Task did not complete."
    ? "task chain status: " + loTaskChain.Status
    release loChilkatGlob
    release loFtp
    release loTaskChain
    return
endif

// 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..
lnNumTasks = loTaskChain.NumTasks
lnTaskIdx = 0

do while (lnTaskIdx < lnNumTasks)

    loTask = loTaskChain.GetTask(lnTaskIdx)

    // 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.
    ? "task status: " + loTask.Status
    ? "task log: " + loTask.ResultErrorText

    release loTask

    lnTaskIdx = lnTaskIdx + 1
enddo

llSuccess = loFtp.Disconnect()


release loChilkatGlob
release loFtp
release loTaskChain