总之,在创建通道、开始异步结果委托或异步结果委托周围使用try/catch块无法捕获连接失败。我希望可以通过该catch块运行ServiceCallError事件。
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();
}
}
以下是堆栈跟踪,供好奇的人参考:
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)
为了实现这一点,我在浏览器中启动应用程序,然后从Visual Studio中终止Web服务器进程。在测试环境中,我可以通过关闭客户端系统的网络连接来获得相同的结果。
以下是完整异常的ToString():
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)
顺便说一下,我能做到的唯一方法是在SL客户端中使用应用程序级别的UnhandledException事件来捕获这个问题。