DataFlex

Cancel HTTP Get Async Task if not Completed after a Max Time

See more HTTP Examples

Demonstrates how to wait a maximum amount of time for an asynchronous task to completed. If not completed in the allotted amount of time, the task is cancelled. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoHttp
    String sUrl
    Variant vTask
    Handle hoTask
    Integer iWaitMaxMs
    Boolean iWasCanceled
    String sResponseStr
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatHttp)) To hoHttp
    If (Not(IsComObjectCreated(hoHttp))) Begin
        Send CreateComObject of hoHttp
    End

    // Set some timeouts, in seconds:
    Set ComConnectTimeout Of hoHttp To 15
    // ReadTimeout specifies the max number of seconds that must elapse when no additional data is received before
    // timing out.  For example, if a server sends a 300 byte response at the rate of 1 byte per second, then
    // ReadTimeout would never cause a timeout because there is never a 15 second interval when nothing arrives.
    Set ComReadTimeout Of hoHttp To 15

    Move "https://your-url.com/something" To sUrl
    Get ComQuickGetStrAsync Of hoHttp sUrl To vTask
    If (IsComObject(vTask)) Begin
        Get Create (RefClass(cComChilkatTask)) To hoTask
        Set pvComObject Of hoTask To vTask
    End
    Get ComRun Of hoTask To iSuccess

    // Wait a maximum of waitMaxMs for the task (i.e. the HTTP GET) to complete.
    // The Wait method returns when the task has been canceled, aborted, or completed, or when the max allotted time has passed.
    Move 20000 To iWaitMaxMs
    Get ComWait Of hoTask iWaitMaxMs To iSuccess

    // At this point, the GET may or may not have completed.  
    // Rather than checking the Task status, we can call task.Cancel because
    // if the Task is no longer running (because it already completed, was canceled or aborted), then the 
    // call to Cancel is a NO-OP (meaning it does nothing and the Task's status is unaffected).
    // Also, task.Cancel returns True if the task was in the "queued" or "running" state and was canceled or aborted. 
    // The method returns False if the task has any other status.
    Get ComCancel Of hoTask To iWasCanceled
    If (iWasCanceled = True) Begin
        Showln "The HTTP GET took too long and was canceled."
    End
    Else Begin
        // Find out what happened.
        Get ComStatusInt Of hoTask To iTemp1
        If (iTemp1 = 7) Begin
            // The task completed, which means the background thread's call to QuickGetStr completed
            // with success or failure.  Find out which...
            Get ComTaskSuccess Of hoTask To bTemp1
            If (bTemp1 = True) Begin
                // Get the string response for the call to QuickGetStr (which happened in Chilkat's background thread).
                Get ComGetResultString Of hoTask To sResponseStr
                Showln sResponseStr
                Showln "HTTP GET successful!"
            End
            Else Begin
                Showln "HTTP GET failed prior to waitMaxMs..."
                Get ComResultErrorText Of hoTask To sTemp1
                Showln sTemp1
            End

        End
        Else Begin
            // The task must've been canceled or aborted by some other means..
            Get ComStatus Of hoTask To sTemp1
            Showln "Task did not complete.  Final status: " sTemp1
        End

    End

    Send Destroy of hoTask


End_Procedure