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POWCF ASynchronous calls within a Windows forms Application using a timer
 

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  1. POWCF ASynchronous calls within a Windows forms Application using a timer
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    <p>I am new to developing with Windows forms applications and I have an issue I could do with some help / guidance on the best practice approach I should be taking.</p> <p>Background:</p> <p>I have an forms based application that needs to refresh every minute with data from a WCF service and then update the UI with the latest results in a List View control. I have this all working in principal but the application crashes intermittently and I need to resolve this. I have stripped out the main parts of the code below. The actual nuts and bolts are probably not required.</p> <p>Code:</p> <pre><code>public partial class Form1 : Form { readonly MatchServiceReference.MatchServiceClient _client = new MatchServiceReference.MatchServiceClient(); public Form1() { _client.GetMMDataCompleted += new EventHandler&lt;GetMMDataCompletedEventArgs&gt;(_client_GetMMDataCompleted); } //Arm Timer private void ArmTimer(object sender, EventArgs e) { aTimer = new Timer(); aTimer.Elapsed += OnTimedEvent; aTimer.Interval = 60000; aTimer.Enabled = true; } //Timer elapsed event private void OnTimedEvent(object source, ElapsedEventArgs e) { try { LoadMatches(); if (LastUpdated.InvokeRequired) { LastUpdated.Invoke(new MethodInvoker(delegate { LastUpdated.Text = e.SignalTime.ToString(); })); } } catch (Exception exception) { } } //Load matches private void LoadMatches() { try { aTimer.Enabled = false; _client.GetMMDataAsync(); } catch (Exception e) { //EventLog.WriteEntry("Application", e.InnerException.ToString(), EventLogEntryType.Error); aTimer.Enabled = true; } } void _client_GetMMDataCompleted(object sender, GetMMDataCompletedEventArgs e) { if (e.Result != null) { var matches = e.Result; Debug.WriteLine("Matches received from service"); if (!IsHandleCreated &amp;&amp; !IsDisposed) return; // Invoke an anonymous method on the thread of the form. Invoke((MethodInvoker) delegate { try { LoadTheMonitorMatches(matches); } catch (Exception exception) { Debug.WriteLine("INNER EXCEPTION" + exception.InnerException); Debug.WriteLine("EXCEPTION MESSAGE" + exception.Message); } }); } aTimer.Enabled = true; } } </code></pre> <p>}</p> <p>Exception:</p> <p>The exception I am getting is as follows -</p> <blockquote> <p>Exception Info: System.Reflection.TargetInvocationException Stack: at System.ComponentModel.AsyncCompletedEventArgs.RaiseExceptionIfNecessary() at MM.MatchServiceReference.GetMMDataCompletedEventArgs.get_Result() at MM.Form1._client_GetMMDataCompleted(System.Object, MM.MatchServiceReference.GetMMDataCompletedEventArgs) at MM.MatchServiceReference.MatchServiceClient.OnGetMMDataCompleted(System.Object) at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(System.Object) at System.Threading.ExecutionContext.runTryCode(System.Object) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode, CleanupCode, System.Object) at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object) at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean) at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()</p> </blockquote> <p>Any help / advice with this would be greatly appreciated.</p> <p>Cheers</p>
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