Hi there.

I'm having a big problem when calling a web service from my WPF application. The application/window locks until the process has completed. I've attempted to run this asynchronously but the problem still persists.

Currently, the web service call I'm making can last 45-60 seconds. It runs a process on the server to fetch a big chunk of data. As it take a little while I wanted to have a progress bar moving indeterminately for the user to see that the application hasn't stalled or anything (you know how impatatient they get).

So:

    private void btnSelect_Click(object sender, RoutedEventArgs e)
    {
        wDrawingList = new WindowDrawingList(systemManager);

        AsyncMethodHandler caller = default(AsyncMethodHandler);

        caller = new AsyncMethodHandler(setupDrawingList);

        // open new thread with callback method 
        caller.BeginInvoke((Guid)((Button)sender).Tag, MyAsyncCallback, null);
    }

Click a button and the app will create the form that the async stuff will be posted to and set up the async stuff calling the async method.

    public bool setupDrawingList(Guid ID)
    {
        if (systemManager.set(ID))
        {
            wDrawingList.Dispatcher.Invoke(DispatcherPriority.Background, new Action(() =>
            {
                wDrawingList.ShowForm();
                Hide();
            }));

            return true;
        }

        return false;
    }

This is the async method. The showForm method contains the calls to setup the new form including the monster web service call

    public void MyAsyncCallback(IAsyncResult ar)
    {
        // Because you passed your original delegate in the asyncState parameter of the Begin call, you can get it back here to complete the call.
        MethodDelegate dlgt = (MethodDelegate)ar.AsyncState;

        // Complete the call.
        bool output = dlgt.EndInvoke(ar);

        try
        {
            // Retrieve the delegate. 
            AsyncResult result = (AsyncResult)ar;
            AsyncMethodHandler caller = (AsyncMethodHandler)result.AsyncDelegate;

            // Because this method is running from secondary thread it can never access ui objects because they are created 
            // on the primary thread.

            // Call EndInvoke to retrieve the results. 
            bool returnValue = caller.EndInvoke(ar);

            // Still on secondary thread, must update ui on primary thread 
            UpdateUI(returnValue == true ? "Success" : "Failed");
        }
        catch (Exception ex)
        {
            string exMessage = null;
            exMessage = "Error: " + ex.Message;
            UpdateUI(exMessage);
        }
    }

    public void UpdateUI(string outputValue)
    {
        // Get back to primary thread to update ui 
        UpdateUIHandler uiHandler = new UpdateUIHandler(UpdateUIIndicators);
        string results = outputValue;

        // Run new thread off Dispatched (primary thread) 
        this.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Normal, uiHandler, results);
    }

    public void UpdateUIIndicators(string outputValue)
    {
        // update user interface controls from primary UI thread
        sbi3.Content = "Processing Completed.";
    }

Any help or theories are appreciated. I'm at a loss.

Thanks in advance