DataFlex

Async Task Chain (another example)

See more Async Examples

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

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoFtp
    Handle hoTaskChain
    Variant vTask
    Handle hoTask
    String sLocalFilename
    String sRemoteFilename
    Integer iNumTasks
    Integer iTaskIdx
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

    Move False To iSuccess

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

    Move False To iSuccess

    Get Create (RefClass(cComChilkatFtp2)) To hoFtp
    If (Not(IsComObjectCreated(hoFtp))) Begin
        Send CreateComObject of hoFtp
    End

    Set ComHostname Of hoFtp To "ftp.example.com"
    Set ComUsername Of hoFtp To "login"
    Set ComPassword Of hoFtp To "password"

    // Connect and login to the FTP server.
    Get ComConnect Of hoFtp To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoFtp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatTaskChain)) To hoTaskChain
    If (Not(IsComObjectCreated(hoTaskChain))) Begin
        Send CreateComObject of hoTaskChain
    End

    // Create a task to change to the remote directory where the file will be uploaded.
    Get ComChangeRemoteDirAsync Of hoFtp "junk" To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End
    Get ComLastMethodSuccess Of hoFtp To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoFtp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Add this task to the task chain.
    Get ComAppend Of hoTaskChain vTask To iSuccess
    Send Destroy of hoTask

    // Create a task to upload a file.
    Move "c:/temp/hamlet.xml" To sLocalFilename
    Move "hamlet.xml" To sRemoteFilename

    Get ComPutFileAsync Of hoFtp sLocalFilename sRemoteFilename To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End
    Get ComLastMethodSuccess Of hoFtp To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoFtp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Add this task to the task chain.
    Get ComAppend Of hoTaskChain vTask To iSuccess
    Send Destroy of hoTask

    // 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.
    Set ComStopOnFailedTask Of hoTaskChain To True
    Get ComRun Of hoTaskChain To iSuccess
    If (Not iSuccess) Begin
        Get ComLastErrorText Of hoTaskChain To sTemp1
        Showln sTemp1
        Procedure_Return
    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 ((ComFinished(hoTaskChain)) <> True)

        // Sleep 100 ms.
        Send ComSleepMs To hoTaskChain 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:
    Get ComStatusInt Of hoTaskChain To iTemp1
    If (iTemp1 <> 7) Begin
        Showln "Task did not complete."
        Get ComStatus Of hoTaskChain To sTemp1
        Showln "task chain status: " sTemp1
        Procedure_Return
    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..
    Get ComNumTasks Of hoTaskChain To iNumTasks
    Move 0 To iTaskIdx

    While (iTaskIdx < iNumTasks)

        Get ComGetTask Of hoTaskChain iTaskIdx To vTask
        If (IsComObject(vTask)) Begin
            Get Create (RefClass(cComChilkatTask)) To hoTask
            Set pvComObject Of hoTask To vTask
        End

        // 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.
        Get ComStatus Of hoTask To sTemp1
        Showln "task status: " sTemp1
        Get ComResultErrorText Of hoTask To sTemp1
        Showln "task log: " sTemp1

        Send Destroy of hoTask

        Move (iTaskIdx + 1) To iTaskIdx
    Loop

    Get ComDisconnect Of hoFtp To iSuccess


End_Procedure