public interface ClientInterface
    {
        [OperationContract]
        void OnCallback(object aUpdatedObject);

    }

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

        [OperationContract]
        void Subscribe();
        /* */
        [OperationContract]
        TransmissionClass GetInterface();
    }


[KnownType(typeof(TransmissionClass))]
    public class RequestHandler : RequestInterface
    {
        private static int MAXIMUM = 32760;
        internal static RequestHandler Instance;
        private List<ClientInterface> iClients = new List<ClientInterface>();
        ClientInterface channel;

        public RequestHandler()
        {
            Instance = this;
        }

        public TransmissionClass GetInterface()
        {
            Form1.AddText("method invoked by:" + Thread.CurrentContext.ToString());

            List<MySubInterface> tList = new List<MySubInterface>();

            for(int i = MAXIMUM; i >= 0; i--)
            {
                tList.Add(new TransmissionSubclass(i));
            }

            MAXIMUM += 1;
            /* */
            TransmissionClass tTC = new TransmissionClass("invokedMethod", tList);
            Form1.AddText("created:" + tTC);
            return tTC;
        }

        public void Subscribe()
        {
            channel = OperationContext.Current.GetCallbackChannel<ClientInterface>();
        }

        public void Send()
        {
            try
            {
                channel.OnCallback("I love deadlines. I like the whooshing sound they make as they fly by.");
            }
            catch (Exception ex)
            {
                Form1.AddText(ex.GetType() + "|" + ex.Message);
            }
        }
    }