(DataFlex) Starting an Asynchronous Task

Chilkat methods that have a name ending in "Async" return a task object. The task object can be run asynchronously on Chilkat's background thread pool. The purpose of this example is to demonstrate how a Task is started via the Run method. It also demonstrates how an application can check on the status of the task, and get the task return value. See the online reference documentation for the full details of the task and task chain objects. Also see the "Task" category on example-code.com for more examples.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoChilkatGlob
    Boolean iSuccess
    Handle hoMailman
    Variant vEmail
    Handle hoEmail
    Variant vTask
    Handle hoTask
    Integer iCurPctDone
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

    // All Chilkat classes can be unlocked at once at the beginning of a program
    // by calling UnlockBundle.  It requires a Bundle unlock code.
    Get Create (RefClass(cComChilkatGlobal)) To hoChilkatGlob
    If (Not(IsComObjectCreated(hoChilkatGlob))) Begin
        Send CreateComObject of hoChilkatGlob
    End
    Get ComUnlockBundle Of hoChilkatGlob "Anything for 30-day trial." To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoChilkatGlob To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatMailMan)) To hoMailman
    If (Not(IsComObjectCreated(hoMailman))) Begin
        Send CreateComObject of hoMailman
    End

    // Set the SMTP server and any required settings.
    Set ComSmtpHost Of hoMailman To "smtp.mymailserver.com"
    Set ComSmtpUsername Of hoMailman To "myLogin"
    Set ComSmtpPassword Of hoMailman To "myPassword"
    Set ComStartTLS Of hoMailman To True

    // Create a new email object
    Get Create (RefClass(cComChilkatEmail)) To hoEmail
    If (Not(IsComObjectCreated(hoEmail))) Begin
        Send CreateComObject of hoEmail
    End

    Set ComSubject Of hoEmail To "This is a test"
    Set ComBody Of hoEmail To "This is a test"
    Set ComFrom Of hoEmail To "Chilkat Support <support@chilkatsoft.com>"
    Get ComAddTo Of hoEmail "Chilkat Admin" "admin@chilkatsoft.com" To iSuccess

    // Call the async version of the SendEmail method to return a task object.
    // The task object is loaded, but is in the Inert state -- meaning it is
    // not yet scheduled to run on Chilkat's background thread pool.
    Get pvComObject of hoEmail to vEmail
    Get ComSendEmailAsync Of hoMailman vEmail To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End
    Get ComLastMethodSuccess Of hoMailman To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoMailman To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Schedule the task for running on the thread pool.  This changes the task's state
    // from Inert to Live.
    Get ComRun Of hoTask To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTask To sTemp1
        Showln sTemp1
        Send Destroy of hoTask
        Procedure_Return
    End

    // The application is now free to do anything else
    // while the email is being sent.

    // For this example, we'll simply sleep and periodically
    // check to see if the SendEmail if finished.  While checking
    // however, we'll report on the progress.
    Move 0 To iCurPctDone
    While ((ComFinished(hoTask)) <> True)

        Get ComPercentDone Of hoTask To iTemp1
        If (iTemp1 <> iCurPctDone) Begin
            Get ComPercentDone Of hoTask To iCurPctDone
            Showln iCurPctDone " percent done"
        End

        // Sleep 100 ms.
        Send ComSleepMs To hoTask 100

    Loop

    // A finished task could be one that was canceled, aborted, or truly finished.  

    // If the task was "canceled", it was canceled prior to actually starting.  This could
    // happen if the task was canceled while waiting in a thread pool queue to be scheduled by Chilkat's
    // background thread pool scheduler.  

    // If the task was "aborted", it indicates that it was canceled while running in a background thread.  
    // The ResultErrorText will likely indicate that the task was aborted.

    // If the task "completed", then it ran to completion, but the actual success/failure of the method
    // is determined by the result obtained via a GetResult* method.  (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 hoTask To iTemp1
    If (iTemp1 <> 7) Begin
        Showln "Task did not complete."
        Get ComStatus Of hoTask To sTemp1
        Showln "task status: " sTemp1
        Send Destroy of hoTask
        Procedure_Return
    End

    // The SendEmail method returns a boolean.  Therefore, after the task is finished,
    // we can get the boolean result by calling GetResultBool.  This is the return value had
    // we called SendEmail synchronously.
    Get ComGetResultBool Of hoTask To iSuccess
    If (iSuccess <> True) Begin
        // The task's ResultErrorText contains what would have been in the LastErrorText property had
        // the SendEmail method been called synchronously.
        Get ComResultErrorText Of hoTask To sTemp1
        Showln sTemp1
    End
    Else Begin
        Showln "Email sent asynchronously."
    End

    Send Destroy of hoTask

    Get ComCloseSmtpConnection Of hoMailman To iSuccess
    If (iSuccess <> True) Begin
        Showln "Connection to SMTP server not closed cleanly."

    End



End_Procedure