实现双工时 WCF 中的超时异常

Question

我的服务合同和回调合同如下所示：

[ServiceContract(CallbackContract = typeof(IWebshopCallback))]
interface IWebshop
{
    [OperationContract]
    string GetWebshopName ();
    [OperationContract]
    string GetProductInfo (Item i);
    [OperationContract]
    List<Item> GetProductList ();
    [OperationContract]
    bool BuyProduct (string i);
    [OperationContract]
    void ConnectNewClient ();
}

[ServiceContract]
interface IWebshopCallback
{
    [OperationContract]
    void NewClientConnected (int totalNrOfConnectedClients);
}

我的服务：

[ServiceBehavior (InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Reentrant)]
class WebshopService : IWebshop
{
  ...
}

在服务内部，我有一个方法可以调用客户端的另一个方法：

public void ConnectNewClient ()
    {
        totalNumber++;
        OperationContext.Current.GetCallbackChannel<IWebshopCallback> ().NewClientConnected (totalNumber);
    }

在客户端，我有一个派生自 IWebshopCallback 的表单，它有一个方法 NewClientConnected(int a)。

问题是，当我尝试运行我的代码时，我运行进入了这个异常：

This request operation sent to http://localhost:4000/IWebshopContract did not receive a reply within the configured timeout (00:00:59.9989895). The time allotted to this operation may have been a portion of a longer timeout.

但是，更奇怪的是，如果我继续我的应用程序的工作，我会发现此功能有效。

是什么导致了这一切？

Answer 1

在服务器端调用函数时需要使用 Task.Run()，所以应该这样：

var callback = OperationContext.Current.GetCallbackChannel<IWebshopCallback> ();
Task.Run (() => callback.NewClientConnected(totalNumber));

而不是这样：

OperationContext.Current.GetCallbackChannel<IWebshopCallback> ().NewClientConnected ();

Answer 2

一般情况下，我们除了双工的行为是客户端returns在调用服务后立即，服务器发回的信息通过回调契约传递。在这种工作模式下，我们把服务契约和回调契约都变成了单向通信。

[OperationContract(Action = "post_num", IsOneWay = true)]
void PostNumber(int n);

我做了一个demo，希望对你有用。

服务器端。

class Program
    {
        static void Main(string[] args)
        {
            using (ServiceHost sh=new ServiceHost(typeof(MyService)))
            {
                ServiceMetadataBehavior smb;
                smb = sh.Description.Behaviors.Find<ServiceMetadataBehavior>();
                if (smb==null)
                {
                    smb = new ServiceMetadataBehavior()
                    {
                        HttpGetEnabled = true
                    };
                    sh.Description.Behaviors.Add(smb);
                }
                sh.Open();
                Console.WriteLine("Service is ready");

                Console.ReadKey();
                sh.Close();
            }
        }
    }
    [ServiceContract(Namespace ="mydomain",Name = "demo", ConfigurationName = "isv", CallbackContract = typeof(ICallback))]
    public interface IDemo
    {
        [OperationContract(Action = "post_num", IsOneWay = true)]
        void PostNumber(int n);
    }
    [ServiceContract]
    public interface ICallback
    {
        [OperationContract(Action = "report", IsOneWay = true)]
        void Report(double progress);
    }

    [ServiceBehavior(ConfigurationName ="sv")]
    public class MyService : IDemo
    {
        public void PostNumber(int n)
        {
            ICallback callback = OperationContext.Current.GetCallbackChannel<ICallback>();
            for (int i = 0; i <=n; i++)
            {
                Task.Delay(500).Wait();
                double p = Convert.ToDouble(i) / Convert.ToDouble(n);
                callback.Report(p);
            }
        }
    }

服务器配置

  <system.serviceModel>
    <services>
      <service name="sv">
        <endpoint address="http://localhost:3333" binding="wsDualHttpBinding" contract="isv"/>
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:3333"/>
          </baseAddresses>
        </host>
      </service>
    </services>
  </system.serviceModel>

客户端。

class Program
{
    static void Main(string[] args)
    {
        DuplexChannelFactory<IDemo> factory = new DuplexChannelFactory<IDemo>(new CallbackHandler(), "test_ep");
        IDemo channel = factory.CreateChannel();
        Console.WriteLine("Start to Call");
        channel.PostNumber(15);
        Console.WriteLine("Calling is done");
        Console.ReadLine();
    }
}
[ServiceContract(Namespace ="mydomain",Name = "demo", ConfigurationName = "isv", CallbackContract = typeof(ICallback))]
public interface IDemo
{
    [OperationContract(Action = "post_num",IsOneWay =true)]
    void PostNumber(int n);
}
[ServiceContract]
public interface ICallback
{
    [OperationContract(Action = "report",IsOneWay =true)]
    void Report(double progress);
}
public class CallbackHandler : ICallback
{
    public void Report(double progress)
    {
        Console.WriteLine("{0:p0}", progress);
    }
}

客户端配置

  <system.serviceModel>
    <client>
      <endpoint name="test_ep" address="http://localhost:3333" binding="wsDualHttpBinding" contract="isv"/>
    </client>
  </system.serviceModel>

结果。

实现双工时 WCF 中的超时异常

TimeOut exception in WCF while implementing duplex

c#

wcf

duplex