Question

server client architecture. No IIS involved. Both applications are WinForm!

I’ve made the following interfaces in a shared Library:

[ServiceContract(SessionMode=SessionMode.Required,
        CallbackContract=typeof(ClientInterface))]
    public interface RequestInterface
    {
        [OperationContract]
        void Subscribe();

        [OperationContract]
        MyInterface GetInterface();
    }

    public interface MyInterface
    {
        [DataMember]
        List<MySubInterface> SubClasses{get;}
    }

    public interface MySubInterface
    {
        [DataMember]
        int Value { get; }
    }

And implemented them on the server like this:

public class RequestHandler : RequestInterface
{
    private List<ClientInterface> iClients = new List<ClientInterface>();

    public MyInterface GetInterface()
    {
        List<MySubInterface> tList = new List<MySubInterface>();
        Form1.AddText("method invoked by:" + Thread.CurrentContext.ToString());
        foreach (RealSubclass tClass in Form1.iClass.SubClasses)
        {
            tList.Add(new TransmissionSubclass(tClass.Value));
        }

        TransmissionClass tTC = new TransmissionClass(tList);
        Form1.AddText("created:" + tTC);
        return tTC;
    }
    public void Subscribe()
    {
        Form1.AddText("subscribing:" + OperationContext.Current.GetCallbackChannel<ClientInterface>());
        iClients.Add(OperationContext.Current.GetCallbackChannel<ClientInterface>());
        fireClassEvent("halloWelt");
    }
}

On the client I’m doing the following piece of code, trying to invoke the GetInterface() method:

        ClientClass tClass = new ClientClass(this);
        DuplexChannelFactory<RequestInterface> pipeFactory =
         new DuplexChannelFactory<RequestInterface>(
            tClass,
            new NetNamedPipeBinding(),
            new EndpointAddress(
               "net.pipe://localhost/Request"));

        RequestInterface pipeProxy = pipeFactory.CreateChannel();

        //pipeProxy.Subscribe(); -- works like a charm
        MyInterface tInterface = pipeProxy.GetInterface(); // doesn't work
        fillListView(tInterface);

However, when debugging through the client step by step the debugging breaks at the marked line and seems to exit this function.
It only returns to ‘step by step’ mode when I close the application’s form.
On the other hand I can see from logging output on my server, that the GetInterface() method gets executed.
The TransmissionClass and TransmissionSubclass are both in the shared library and implement MyInterface / MySubInterface

[DataContract]
[Serializable]
public class TransmissionClass : MyInterface
{
    [DataMember]
    public List<MySubInterface> SubClasses{get;private set;}

    public TransmissionClass(List<MySubInterface> aList)
    {
        SubClasses = aList;
    }

    public override string ToString()
    {
        return "TransmissionClass,Count:" + SubClasses.Count;
    }
}

WCF-initialization on the server side:

using (ServiceHost host = new ServiceHost(
            typeof(RequestHandler),
            new Uri[] { new Uri("net.pipe://localhost") }))
                    {

                        ServiceDebugBehavior tBehavior = new ServiceDebugBehavior();
                        if (null == tBehavior)
                        {
                            host.Description.Behaviors.Add(new ServiceDebugBehavior() { IncludeExceptionDetailInFaults = true });
                        }
                        else if (!tBehavior.IncludeExceptionDetailInFaults)
                        {
                            tBehavior.IncludeExceptionDetailInFaults = true;
                        }
                        host.AddServiceEndpoint(typeof(RequestInterface),
                          new NetNamedPipeBinding(), "Request");

                        host.Open();
                        Application.Run(new Form1());

                        host.Close();
        }

Answer 1

Put the [KnownTypes] attribute to let WCF to know what concrete classes implements your interface.