WCF雙工TCP通信錯誤

Question

我有一個示例服務來測試WCF net.tcp通信。這是非常簡單的服務，它所做的只是向服務訂閱客戶端，然後調用callbackchannel來通知所有連接的客戶端有關廣播消息。該服務託管在IIS 7.5中。

這裏是服務代碼和測試客戶端來測試它。

[ServiceContract(CallbackContract = typeof(ISampleServiceCallBack), SessionMode = SessionMode.Required)] 
public interface ISampleCuratioService 
{ 
    [OperationContract(IsOneWay = true)] 
    void SubcribeToService(string sub); 

    [OperationContract] 
    string GetData(int value); 

    [OperationContract(IsOneWay = true)] 
    void Broadcast(string message); 
} 

public interface ISampleServiceCallBack 
{ 
    [OperationContract(IsOneWay = true)] 
    void NotifyClient(string message); 
} 

這裏的服務實現：

[ServiceBehavior(Name = "CuratioCSMService", InstanceContextMode = InstanceContextMode.PerSession)] 
public class Service1 : ISampleCuratioService 
{ 
    private static List<ISampleServiceCallBack> JoinedClien = new List<ISampleServiceCallBack>(); 

    public void SubcribeToService(string sub) 
    { 
     var subscriber = OperationContext.Current.GetCallbackChannel<ISampleServiceCallBack>(); 
     if (!JoinedClien.Contains(subscriber)) 
     { 
      JoinedClien.Add(subscriber); 
     } 
    } 

    public string GetData(int value) 
    { 
     return string.Format("You entered: {0}", value); 
    } 

    public void Broadcast(string message) 
    { 
     JoinedClien.ForEach(c => c.NotifyClient("message was received " + message)); 
    } 
} 

我不明白運行時，我得到它的行爲。第一個客戶端運行後，一切正常，但在關閉並打開測試客戶端應用程序時，它會拋出異常，通知該通道不能用於通信，因爲它處於故障狀態。

這是樣品測試客戶端：當我運行5個客戶

static void Main(string[] args) 
    { 
     var callneckclient = new ServiceClientProxy(); 
     var client = new SampleCuratioServiceClient(new InstanceContext(callneckclient)); 
     client.SubcribeToService("me"); 
     Console.ReadLine(); 

     for (int i = 0; i < 15; i++) 
     { 
      Console.WriteLine(client.GetData(5)); 
      client.Broadcast("this is from client me"); 
     } 
     client.Close(); 
     Console.Read(); 
    } 

    public class ServiceClientProxy : ISampleCuratioServiceCallback, IDisposable 
    { 
     public void NotifyClient(string message) 
     { 
      Console.WriteLine(message); 
     } 

     public void Dispose() 
     { 
      GC.SuppressFinalize(this); 
     } 
    } 

的情況就會更馬車。不是那些發送或接收消息。

Answer 1

當客戶端調用SubcribeToService時，您將其操作上下文添加到名爲JoinedClien的列表中。

當您在服務器中調用Broadcast時，您將針對每個連接的客戶端在所有收集的操作上下文中調用方法NotifyClient。

問題是，斷開的客戶端不會從您的JoinedClien列表中刪除。 當您嘗試調用斷開的操作上下文的操作方法時，您會收到通道處於錯誤狀態錯誤。

要解決，你應該訂閱Channel_Closed和Channel_Faulted事件，還搭上CommunicationException回撥到您的客戶端時，並移除故障客戶端的操作語境：

public void Broadcast(string message) 
{ 
    // copy list of clients 
    List<OperationContext> clientsCopy = new List<OperationContext>(); 
    lock(JoinedClien) { 
     clientsCopy.AddRange(JoinedClien); 
    } 

    // send message and collect faulted clients in separate list 
    List<OperationContext> clientsToRemove = new List<OperationContext>(); 
    foreach (var c in JoinedClien) 
    { 
     try { 
      c.NotifyClient("message was received " + message)); 
     } 
     catch (CommunicationException ex) { 
      clientsToRemove.Add(c); 
     } 
    } 

    foreach (var c in clientsToRemove) 
    { 
     lock(JoinedClien) { 
      if(JoinedClien.Contains(c)) 
       JoinedClien.Remove(c); 
     } 
    } 
} 

當增加新客戶你也必須鎖定該操作：

var subscriber = OperationContext.Current.GetCallbackChannel<ISampleServiceCallBack>(); 
lock(JoinedClien) 
{ 
    if (!JoinedClien.Contains(subscriber)) 
    { 
     JoinedClien.Add(subscriber); 
    } 
}