當使用WCF回調客戶如何知道如果服務器已中斷

Question

如果我創建了一個WCF服務與提供回調和我有幾個客戶端註冊接收事件呢，怎麼這些客戶知道，如果服務中斷或下降？目前他們正在等待一個永遠不會開火的事件。

我想也許我可以實現某種形式的投票的（這是我試圖從逃脫）。但即使投票似乎是一個可憐的修復。例如，如果我每隔30秒輪詢一次，但服務或應用程序池在下次檢查之前重新啓動，則客戶端會認爲一切正常，儘管服務器失去了對它們的引用。

Answer 1

你可以利用的IClientChannel各種事件監測與連接發生了什麼。對於您的情況，Faulted事件似乎是最合適的。但也有其他事件可能會對您有用。

_proxy.InnerChannel.Opening += OnChannelOpening; 
    _proxy.InnerChannel.Opened += OnChannelOpened; 
    _proxy.InnerChannel.Faulted += OnChannelFaulted; 
    _proxy.InnerChannel.UnknownMessageReceived += OnChannelUnknownMessageReceived; 
    _proxy.InnerChannel.Closing += OnChannelClosing; 
    _proxy.InnerChannel.Closed += OnChannelClosed; 

Answer 2

看一看這個倉庫我寫來回答另一個問題：https://github.com/Aelphaeis/MyWcfDuplexPipeExample/tree/MultiClient

在這個倉庫有雙工連接和兩個客戶端。

如果客戶端斷開連接，並服務嘗試當您嘗試在客戶端調用回調函數，你會應該捕獲CommunicationObjectAbortedException訪問的客戶端。

如果該服務被斷開，客戶端試圖叫你應該試圖捕獲的EndPointNotFoundException服務。

public class MyServiceClient: IMyService, IDisposable 
{ 
    DuplexChannelFactory<IMyService> myServiceFactory { get; set; } 

    public MyServiceClient(IMyServiceCallback Callback) 
    { 
     InstanceContext site = new InstanceContext(Callback); 
     NetNamedPipeBinding binding = new NetNamedPipeBinding(); 
     EndpointAddress endpointAddress = new EndpointAddress(Constants.myPipeService + @"/" + Constants.myPipeServiceName); 

     myServiceFactory = new DuplexChannelFactory<IMyService>(site, binding, endpointAddress); 
     Init(); 
    } 
    public void Init() 
    { 
     myServiceFactory.CreateChannel().Init();//EndPointNotFoundException Thrown here 
    } 

    public void DoWork() 
    { 
     myServiceFactory.CreateChannel().DoWork();//EndPointNotFoundException Thrown here 
    } 

    public void Dispose() 
    { 
     myServiceFactory.Close(); 
    } 
} 

服務

public class MyServiceServer : IDisposable 
{ 
    public Boolean IsDisposed { get; private set; } 
    ServiceHost host { get; set; } 
    MyService service; 
    public void Open() 
    { 
     if (host != null) 
      Dispose(); 

     IsDisposed = false; 
     service = new MyService(); 
     host = new ServiceHost(service, new Uri(Constants.myPipeService)); 
     host.AddServiceEndpoint(typeof(IMyService), new NetNamedPipeBinding(), Constants.myPipeServiceName); 

     host.BeginOpen(OnOpen, host); 
    } 

    public void Msg(int ClientId) 
    { 
     foreach (var cb in service.Callbacks) 
      if (cb.GetClientId() == ClientId) // CommunicationObjectAbortedException here 
       cb.RecieveMessage("We have called you choosen one"); 
    } 

    public void Close() 
    { 
     host.BeginClose(OnClose, host); 
    } 

    public void Dispose() 
    { 
     ((IDisposable)host).Dispose(); 
     IsDisposed = true; 
     host = null; 
    } 

    void OnOpen(IAsyncResult ar) 
    { 
     ServiceHost service = (ServiceHost)ar.AsyncState; 
     service.EndOpen(ar); 
    } 
    void OnClose(IAsyncResult ar) 
    { 
     ServiceHost service = (ServiceHost)ar.AsyncState; 
     service.EndClose(ar); 
     Dispose(); 
    } 
}