Question

我正在尝试使用渠道工厂从此link调用来自Silverlight客户端的WCF服务。与渠道工厂合作对我来说是新鲜事，所以请耐心等待我！

文章中提到的一切都很好。但是现在我正在尝试实现Fault异常，以便我可以捕获Silverlight端的实际异常。但由于某种原因，我总是最终捕捉到不符合我目的的CommunicationException。

这是我的服务合同：

[OperationContract]
[FaultContract(typeof(Fault))]
IList<Category> GetCategories();

抓住服务块：

    catch (Exception ex)
    {
        Fault fault = new Fault(ex.Message);
        throw new FaultException<Fault>(fault, "Error occured in the GetCategories service");
    }

具有异步模式的客户的服务合同：

[OperationContract(AsyncPattern = true)]
[FaultContract(typeof(Fault))]
IAsyncResult BeginGetCategories(AsyncCallback callback, object state);

IList<Category> EndGetCategories(IAsyncResult result);

以下是来自客户的服务电话：

        ICommonServices channel = ChannelProviderFactory.CreateFactory<ICommonServices>(COMMONSERVICE_URL, false);
        var result = channel.BeginGetCategories(
            (asyncResult) =>
            {
                try
                {
                    var returnval = channel.EndGetCategories(asyncResult);
                    Deployment.Current.Dispatcher.BeginInvoke(() =>
                    {
                        CategoryCollection = new ObservableCollection<Category>(returnval);
                    });
                }
                catch (FaultException<Fault> serviceFault)
                {
                    MessageBox.Show(serviceFault.Message);
                }
                catch (CommunicationException cex)
                {
                    MessageBox.Show("Unknown Communications exception occured.");
                }
            }, null
            );

我在服务和客户端应用程序之间共享DataContract .dll，因此它们指的是相同的数据协定类（类别和故障）

请告诉我我做错了什么？

更新：我确实清楚地看到了Fiddler中服务发送的故障异常。这让我相信我在客户端缺少一些东西。

Answer 1

要在sivleright中捕获常规异常，您必须创建“启用Silverlight的WCF服务”（添加 - >新项 - ＆gt;启用Silverlight的WCF服务）。如果您已经创建了标准WCF服务，则可以手动将属性[SilverlightFaultBehavior]添加到服务中。此属性的默认实现是：

    public class SilverlightFaultBehavior : Attribute, IServiceBehavior
{
    private class SilverlightFaultEndpointBehavior : IEndpointBehavior
    {
        public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
        {
        }

        public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
        {
        }

        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
        {
            endpointDispatcher.DispatchRuntime.MessageInspectors.Add(new SilverlightFaultMessageInspector());
        }

        public void Validate(ServiceEndpoint endpoint)
        {
        }

        private class SilverlightFaultMessageInspector : IDispatchMessageInspector
        {
            public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
            {
                return null;
            }

            public void BeforeSendReply(ref Message reply, object correlationState)
            {
                if ((reply != null) && reply.IsFault)
                {
                    HttpResponseMessageProperty property = new HttpResponseMessageProperty();
                    property.StatusCode = HttpStatusCode.OK;
                    reply.Properties[HttpResponseMessageProperty.Name] = property;
                }
            }
        }
    }

    public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters)
    {
    }

    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
        foreach (ServiceEndpoint endpoint in serviceDescription.Endpoints)
        {
            endpoint.Behaviors.Add(new SilverlightFaultEndpointBehavior());
        }
    }

    public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
    }
}

Answer 2

我们在服务器上使用自己的自定义ServiceException类，例如

[Serializable]
public class ServiceException : Exception
{
    public ServiceException()
    {

    }

    public ServiceException(string message, Exception innerException)
        : base(message, innerException)
    {

    }

    public ServiceException(Exception innerException)
        : base("Service Exception Occurred", innerException)
    {

    }

    public ServiceException(string message)
        : base(message)
    {

    }
}

然后在我们的服务器端服务方法中，我们使用这样的错误处理：

        try
        {
        ......
        }
        catch (Exception ex)
        {
            Logger.GetLog(Logger.ServiceLog).Error("MyErrorMessage", ex);
            throw new ServiceException("MyErrorMessage", ex);
        }

然后我们对所有Web服务调用使用通用方法：

    /// <summary>
    /// Runs the given functon in a try catch block to wrap service exception.
    /// Returns the result of the function.
    /// </summary>
    /// <param name="action">function to run</param>
    /// <typeparam name="T">Return type of the function.</typeparam>
    /// <returns>The result of the function</returns>
    protected T Run<T>(Func<T> action)
    {
        try
        {
            return action();
        }
        catch (ServiceException ex)
        {
            ServiceLogger.Error(ex);
            throw new FaultException(ex.Message, new FaultCode("ServiceError"));
        }
        catch (Exception ex)
        {
            ServiceLogger.Error(ex);
            throw new FaultException(GenericErrorMessage, new FaultCode("ServiceError"));
        }
    }

使用Channel Factory在Silverlight中捕获故障异常

2 个答案: