Estou tentando escrever uma classe que encapsula as chamadas do WCF (o cliente é o Silverlight, se isso for importante). Tudo funciona bem, mas não sei como interceptar uma falha de conexão, como se o servidor não respondesse. Parece que um pouco de trabalho acontece em algum lugar no código resultante do ChannelFactory, mas não tenho certeza. Revisão geral de código é bem-vinda também. :)

A linha inferior, em torno da criação do canal, ou o delegado de início ou assíncrono do resultado no try / catch não interceptam uma conexão com falha. Eu gostaria de ter essa captura executar o evento ServiceCallError.

public class ServiceCaller : IDisposable
{
    private IFeedService _channel;

    public ServiceCaller()
    {
        var elements = new List<BindingElement>();
        elements.Add(new BinaryMessageEncodingBindingElement());
        elements.Add(new HttpTransportBindingElement());
        var binding = new CustomBinding(elements);
        var endpointAddress = new EndpointAddress(App.GetRootUrl() + "Feed.svc");
        _channel = new ChannelFactory<IFeedService>(binding, endpointAddress).CreateChannel();
    }

    public void MakeCall(DateTime lastTime, Dictionary<string, string> context)
    {
        AsyncCallback asyncCallBack = delegate(IAsyncResult result)
        {
            var items = ((IFeedService)result.AsyncState).EndGet(result);
            if (ItemsRetrieved != null)
                ItemsRetrieved(this, new ServiceCallerEventArgs(items));
        };
        _channel.BeginGet(lastTime, context, asyncCallBack, _channel);
    }

    public event ItemsRetrievedEventHandler ItemsRetrieved;
    public event ServiceCallErrorHandler ServiceCallError;

    public delegate void ItemsRetrievedEventHandler(object sender, ServiceCallerEventArgs e);

    public delegate void ServiceCallErrorHandler(object sender, ServiceCallErrorEventArgs e);

    public void Dispose()
    {
        _channel.Close();
        _channel.Dispose();
    }
}

Aqui está o rastreamento de pilha, para aqueles que estão curiosos:

 An AsyncCallback threw an exception.
at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously)
   at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously, Exception exception)
   at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.OnGetResponse(IAsyncResult result)
   at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClassd.<InvokeGetResponseCallback>b__b(Object state2)
   at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)

Para que isso aconteça, eu inicio o aplicativo no navegador e mato o processo do servidor Web do Visual Studio. Em um ambiente de teste, obtenho a mesma coisa matando a conexão de rede para o sistema do cliente.

Aqui está o ToString () da exceção FULL:

System.Exception: An AsyncCallback threw an exception. ---> System.Exception: An AsyncCallback threw an exception. ---> System.ServiceModel.CommunicationException: The remote server returned an error: NotFound. ---> System.Net.WebException: The remote server returned an error: NotFound. ---> System.Net.WebException: The remote server returned an error: NotFound.
   at System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
   at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
   at System.Net.Browser.AsyncHelper.<>c__DisplayClass2.<BeginOnUI>b__0(Object sendState)
   --- End of inner exception stack trace ---
   at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
   at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
   at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.CompleteGetResponse(IAsyncResult result)
   --- End of inner exception stack trace ---
   at System.ServiceModel.Channels.Remoting.RealProxy.Invoke(Object[] args)
   at proxy_2.EndGet(IAsyncResult )
   at CoasterBuzz.Feed.Client.ServiceCaller.<MakeCall>b__0(IAsyncResult result)
   at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously)
   --- End of inner exception stack trace ---
   at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously)
   at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously, Exception exception)
   at System.ServiceModel.Channels.ServiceChannel.SendAsyncResult.CallComplete(Boolean completedSynchronously, Exception exception)
   at System.ServiceModel.Channels.ServiceChannel.SendAsyncResult.FinishSend(IAsyncResult result, Boolean completedSynchronously)
   at System.ServiceModel.Channels.ServiceChannel.SendAsyncResult.SendCallback(IAsyncResult result)
   at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously)
   --- End of inner exception stack trace ---
   at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously)
   at System.ServiceModel.AsyncResult.Complete(Boolean completedSynchronously, Exception exception)
   at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.OnGetResponse(IAsyncResult result)
   at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClassd.<InvokeGetResponseCallback>b__b(Object state2)
   at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)

By the way, a única maneira que eu posso pegar isso é usar o evento UnhandledException nível de aplicativo no cliente SL.