PowerBuilder

Async Task Chain (another example)

See more Async Examples

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

integer li_rc
integer li_Success
oleobject loo_Ftp
oleobject loo_TaskChain
oleobject loo_Task
string ls_LocalFilename
string ls_RemoteFilename
integer li_NumTasks
integer li_TaskIdx

li_Success = 0

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

li_Success = 0

loo_Ftp = create oleobject
li_rc = loo_Ftp.ConnectToNewObject("Chilkat.Ftp2")
if li_rc < 0 then
    destroy loo_Ftp
    MessageBox("Error","Connecting to COM object failed")
    return
end if

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

// Connect and login to the FTP server.
li_Success = loo_Ftp.Connect()
if li_Success <> 1 then
    Write-Debug loo_Ftp.LastErrorText
    destroy loo_Ftp
    return
end if

loo_TaskChain = create oleobject
li_rc = loo_TaskChain.ConnectToNewObject("Chilkat.TaskChain")

// Create a task to change to the remote directory where the file will be uploaded.
loo_Task = loo_Ftp.ChangeRemoteDirAsync("junk")
if loo_Ftp.LastMethodSuccess = 0 then
    Write-Debug loo_Ftp.LastErrorText
    destroy loo_Ftp
    destroy loo_TaskChain
    return
end if

// Add this task to the task chain.
li_Success = loo_TaskChain.Append(loo_Task)
destroy loo_Task

// Create a task to upload a file.
ls_LocalFilename = "c:/temp/hamlet.xml"
ls_RemoteFilename = "hamlet.xml"

loo_Task = loo_Ftp.PutFileAsync(ls_LocalFilename,ls_RemoteFilename)
if loo_Ftp.LastMethodSuccess = 0 then
    Write-Debug loo_Ftp.LastErrorText
    destroy loo_Ftp
    destroy loo_TaskChain
    return
end if

// Add this task to the task chain.
li_Success = loo_TaskChain.Append(loo_Task)
destroy loo_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.
loo_TaskChain.StopOnFailedTask = 1
li_Success = loo_TaskChain.Run()
if not li_Success then
    Write-Debug loo_TaskChain.LastErrorText
    destroy loo_Ftp
    destroy loo_TaskChain
    return
end if

// 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 loo_TaskChain.Finished <> 1

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

loop

// 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 loo_TaskChain.StatusInt <> 7 then
    Write-Debug "Task did not complete."
    Write-Debug "task chain status: " + loo_TaskChain.Status
    destroy loo_Ftp
    destroy loo_TaskChain
    return
end if

// 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..
li_NumTasks = loo_TaskChain.NumTasks
li_TaskIdx = 0

do while (li_TaskIdx < li_NumTasks)

    loo_Task = loo_TaskChain.GetTask(li_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.
    Write-Debug "task status: " + loo_Task.Status
    Write-Debug "task log: " + loo_Task.ResultErrorText

    destroy loo_Task

    li_TaskIdx = li_TaskIdx + 1
loop

li_Success = loo_Ftp.Disconnect()


destroy loo_Ftp
destroy loo_TaskChain