WCF - Publisher-Subscriber - Subscription Problem

Question

Publisher Interface

[ServiceContract]
    public interface IPublisherInterface
    {
        [OperationContract(IsOneWay = false)]
        void Publish(MessageClass e, string topicName);

    }

Subscriber Interface

[ServiceContract(CallbackContract = typeof(IPublisherInterface))]
    public interface ISubscriberInterface
    {
        [OperationContract]
        void Subscribe(string topicName);

        [OperationContract]
        void UnSubscribe(string topicName);
    }

Subscriber Program

class Program
    {
        static void Main(string[] args)
        {
            DuplexChannelFactory<ISubscriberInterface> namedPipeFactory =
               new DuplexChannelFactory<ISubscriberInterface>(
                    new InstanceContext(new PublisherService()),
                  new NetNamedPipeBinding(),
                  new EndpointAddress("net.pipe://localhost/Sub"));

            ISubscriberInterface pipeProxy = namedPipeFactory.CreateChannel();
            pipeProxy.Subscribe("name");

            //SubscriberForm f = new SubscriberForm(pipeProxy);
            //f.ShowDialog();
        }
    }

Why am I getting this message?

The message with Action 'http://tempuri.org/ISubscriberInterface/Subscribe' cannot be
 processed at the receiver, due to a ContractFilter mismatch at the EndpointDispatcher. 
This may be because of either a contract mismatch (mismatched Actions between sender and 
receiver) or a binding/security mismatch between the sender and the receiver.  Check that
 sender and receiver have the same contract and the same binding (including security 
requirements, e.g. Message, Transport, None)."

This is my Host

class Program
    {
        static void Main(string[] args)
        {
            ServiceHost _publisherServiceHost = new ServiceHost(typeof(PublisherService), new Uri[] { new Uri("net.pipe://localhost/") });
            _publisherServiceHost.AddServiceEndpoint(
                    typeof(IPublisherInterface),
                    new NetNamedPipeBinding(),
                    "Pub");
            _publisherServiceHost.Open();

            ServiceHost _subscriberServiceHost = new ServiceHost(typeof(PublisherService), new Uri[] { new Uri("net.pipe://localhost/") });
            _subscriberServiceHost.AddServiceEndpoint(
                    typeof(IPublisherInterface),
                    new NetNamedPipeBinding(),
                    "Sub");
            _subscriberServiceHost.Open();

            Console.WriteLine("Server is Running.");
            Console.ReadLine();
        }
    }

Answer 1

Are you sure with the second host opening? Shouldn't it be:

    ServiceHost _subscriberServiceHost = new ServiceHost(typeof(SubscriberService), new Uri[] { new Uri("net.pipe://localhost/sub") });
    _subscriberServiceHost.AddServiceEndpoint(
            typeof(ISubscriberInterface),
            new NetNamedPipeBinding(),
            "Sub");
    _subscriberServiceHost.Open();

I'm guessing the names, but I guess that probably the name you given to your ISubscriberInterface implementation.

Answer 2

I think, your problem is here:

_subscriberServiceHost.AddServiceEndpoint(
                typeof(IPublisherInterface),
                new NetNamedPipeBinding(),
                "Sub");

The Subscriber service host is created using IPublisherInterface contract, which is wrong. It should be ISubscriberInterface instead