DataFlex

Async Methods Returning an Object

See more Async Examples

Demonstrates how to call an asynchronous method that returns an object. This example reads email from a POP3 server using the Async versions of the Chilkat methods. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoMailman
    Variant vTask
    Handle hoTask
    Integer iMaxWaitMs
    Integer iNumMessages
    Handle hoEmail
    Integer i
    String sTemp1
    String sTemp2
    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(cComChilkatMailMan)) To hoMailman
    If (Not(IsComObjectCreated(hoMailman))) Begin
        Send CreateComObject of hoMailman
    End

    // Set the POP3 server's hostname
    Set ComMailHost Of hoMailman To "pop.example.com"

    // Set the POP3 login/password and any other requirements..
    Set ComPopUsername Of hoMailman To "myLogin"
    Set ComPopPassword Of hoMailman To "myPassword"
    Set ComPopSsl Of hoMailman To True
    Set ComMailPort Of hoMailman To 995

    // Connect to the POP3 server:
    Get ComPop3BeginSessionAsync Of hoMailman 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

    // Start the background task.
    Get ComRun Of hoTask To iSuccess
    If (Not iSuccess) Begin
        Get ComLastErrorText Of hoTask To sTemp1
        Showln sTemp1
        Send Destroy of hoTask
        Procedure_Return
    End

    // Wait for the POP3 connect task to finish.
    // The True/False returned by Wait applies to the Wait method call, not the task.
    Move 30000 To iMaxWaitMs
    Get ComWait Of hoTask iMaxWaitMs To iSuccess
    Get ComStatusInt Of hoTask To iTemp1
    Get ComTaskSuccess Of hoTask To bTemp1
    If (Not iSuccess Or (iTemp1 <> 7) Or (bTemp1 <> True)) Begin
        If (Not iSuccess) Begin
            // The task.LastErrorText applies to the Wait method call.
            Get ComLastErrorText Of hoTask To sTemp1
            Showln sTemp1
        End
        Else Begin
            // The ResultErrorText applies to the underlying task method call (i.e. the Pop3BeginSession)
            Get ComStatus Of hoTask To sTemp1
            Showln sTemp1
            Get ComResultErrorText Of hoTask To sTemp1
            Showln sTemp1
        End

        Send Destroy of hoTask
        Procedure_Return
    End

    Send Destroy of hoTask

    // Get the number of messages in the mailbox.
    Get ComGetMailboxCountAsync Of hoMailman To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End

    // To keep the example short, we'll skip handling failures.
    // The failures would be handled in the same way as shown above.

    Get ComRun Of hoTask To iSuccess
    Get ComWait Of hoTask iMaxWaitMs To iSuccess
    Get ComGetResultInt Of hoTask To iNumMessages
    Send Destroy of hoTask
    If (iNumMessages = 0) Begin
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatEmail)) To hoEmail
    If (Not(IsComObjectCreated(hoEmail))) Begin
        Send CreateComObject of hoEmail
    End

    For i From 1 To iNumMessages

        Get ComFetchByMsgnumAsync Of hoMailman i 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

        Get ComRun Of hoTask To iSuccess
        Get ComWait Of hoTask iMaxWaitMs To iSuccess
        Get ComStatusInt Of hoTask To iTemp1
        Get ComTaskSuccess Of hoTask To bTemp1
        If (Not iSuccess Or (iTemp1 <> 7) Or (bTemp1 <> True)) Begin
            If (Not iSuccess) Begin
                // The task.LastErrorText applies to the Wait method call.
                Get ComLastErrorText Of hoTask To sTemp1
                Showln sTemp1
            End
            Else Begin
                // The ResultErrorText applies to the underlying task method call (i.e. the FetchByMsgnum)
                Get ComStatus Of hoTask To sTemp1
                Showln sTemp1
                Get ComResultErrorText Of hoTask To sTemp1
                Showln sTemp1
            End

            Send Destroy of hoTask
            Procedure_Return
        End

        // Each Chilkat object that can be a return value of an asynchronous task will
        // have a method named LoadTaskResult.  The object returned in the underlying
        // asynchronous method call is retrieved by calling LoadTaskResult. 

        // To say it another way: The application will provide a pre-existing object of
        // the desired return type (in this case it is an email object).  This object is
        // loaded by calling LoadTaskResult.  

        Get ComLoadTaskResult Of hoEmail vTask To iSuccess
        Send Destroy of hoTask

        If (Not iSuccess) Begin
            Get ComLastErrorText Of hoEmail To sTemp1
            Showln sTemp1
            Procedure_Return
        End
        Else Begin
            Get ComFrom Of hoEmail To sTemp1
            Get ComSubject Of hoEmail To sTemp2
            Showln sTemp1 ": " sTemp2 (character(10))
        End

    Loop



End_Procedure