检测客户端死亡WCF双工协定(Detecting Client Death in WCF Duple

我试图建立一个SOA，在这里客户可以在服务器上执行长时间运行的查询和服务器响应使用回调。

我希望能够在客户端断开检测（通过用户启动的关机，未处理的异常或丢失网络连接），使服务器可以选择取消昂贵的请求。

我测试了各种失败的案例，但我似乎无法得到某些事件处理火灾。

测试失败的案例：杀害该客户端进程的请求之后。使用程序一样CurrPorts关闭TCP连接。

测试代码：

using System;
using System.ServiceModel;
using System.Threading;

namespace WCFICommunicationObjectExperiments
{
    class Program
    {
        static void Main(string[] args)
        {
            var binding = new NetTcpBinding(SecurityMode.None);

            var serviceHost = new ServiceHost(typeof (Server));
            serviceHost.AddServiceEndpoint(typeof (IServer), binding, "net.tcp://localhost:5000/Server");
            serviceHost.Open();
            Console.WriteLine("Host is running, press <ENTER> to exit.");
            Console.ReadLine();
        }

    }

    [ServiceContract(CallbackContract = typeof(IClient))]
    public interface IServer
    {
        [OperationContract]
        void StartProcessing(string Query);
    }

    public interface IClient
    {
        [OperationContract]
        void RecieveResults(string Results);
    }

    [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple)]
    public class Server : IServer
    {

        public void StartProcessing(string Query)
        {
            Thread.Sleep(5000);

            //Callback Channel
            var clientCallback = OperationContext.Current.GetCallbackChannel<IClient>();
            var clientCallbackCommunicationObject = ((ICommunicationObject) clientCallback);
            EventHandler faultedHandlerCallback = (o, s) => Console.WriteLine("Client Channel Faulted.");
            EventHandler closedHandlerCallback = (o, s) => Console.WriteLine("Client Channel Closed.");
            clientCallbackCommunicationObject.Faulted += faultedHandlerCallback;
            clientCallbackCommunicationObject.Closed += closedHandlerCallback;

            //Request Channel
            var requestChannel = OperationContext.Current.Channel;
            EventHandler faultedHandlerRequest = (o, s) => Console.WriteLine("Request Channel Faulted.");
            EventHandler closedHandlerRequest = (o, s) => Console.WriteLine("Request Channel Closed.");
            requestChannel.Faulted += faultedHandlerRequest;
            requestChannel.Closed += closedHandlerRequest;

            try
            {
                clientCallback.RecieveResults("42.");
            }
            catch (CommunicationObjectAbortedException ex)
            {
                Console.WriteLine("Client Aborted the connection");
            }
            catch (CommunicationObjectFaultedException ex)
            {
                Console.WriteLine("Client Died.");
            }
            clientCallbackCommunicationObject.Faulted -= faultedHandlerCallback;
            clientCallbackCommunicationObject.Faulted -= closedHandlerCallback;
            requestChannel.Faulted -= faultedHandlerRequest;
            requestChannel.Closed -= closedHandlerRequest;
        }
    }

    public class ClientToTestStates : IClient
    {
        private IServer m_Server;

        private readonly ManualResetEvent m_ReceivedEvent = new ManualResetEvent(false);
        private readonly ManualResetEvent m_ChannelFaulted = new ManualResetEvent(false);
        private readonly ManualResetEvent m_ChannelClosed = new ManualResetEvent(false);

        public ClientToTestStates()
        {
            var binding = new NetTcpBinding(SecurityMode.None);
            var channelFactory = new DuplexChannelFactory<IServer>(this, binding, new EndpointAddress("net.tcp://localhost:5000/Server"));
            m_Server = channelFactory.CreateChannel();
            ((ICommunicationObject)m_Server).Open();
            ((ICommunicationObject)m_Server).Faulted += ChannelFaulted;
            ((ICommunicationObject)m_Server).Closed += ChannelClosed;

            m_Server.StartProcessing("What is the answer?");

            WaitHandle.WaitAny(new WaitHandle[] {m_ReceivedEvent, m_ChannelFaulted, m_ChannelClosed});
        }

        void ChannelFaulted(object sender, EventArgs e)
        {
            m_ChannelFaulted.Set();
            Console.WriteLine("Channel Faulted.");
        }

        void ChannelClosed(object sender, EventArgs e)
        {
            m_ChannelClosed.Set();
            Console.WriteLine("Channel Closed.");
        }


        public void RecieveResults(string results)
        {
            m_ReceivedEvent.Set();
            Console.WriteLine("Recieved Results {0}", results);
        }
    }
}

什么是处理这些各种各样的故障情况下，最好的做法呢？我希望能够使用底层TCP连接，以检测其中的一些东西。

Answer 1:

在他的“编程WCF服务的书，朱瓦尔·洛解释说，WCF不提供管理服务回调一个mechansim，而这必须由服务端和客户端明确地进行管理。如果服务试图调用已关闭客户端上的回调，一个的ObjectDisposedException将在服务信道被抛出。

他建议增加一个连接和断开的方法来服务合同 - 因为回调必须提供给当这些被调用，服务可管理客户端回调的服务。然后由该客户端，以确保它调用断开连接时，它不再希望从服务收到回调，并调用回调到客户端时，该服务必须处理任何异常。

Answer 2:

试试这个检查，如果回调对象仍然是有效的：

(((ICommunicationObject)myCallbackObject).State == CommunicationState.Opened)

myCallbackObject在这种情况下，通过它可以执行回调的目标，即实现一个回调协定