Getting to know WCF questions.

[Snowjim]

Hey! I am building on a simple chat application that uses callbacks. The contract are created in a class library that are then referd to in myWCFCallBackHost, the contract looks like this: Contract: namespace myWCFCallBackService { /// /// The interface the service exposes /// One Session to each client /// [ServiceContract(SessionMode=SessionMode.Required, CallbackContract = typeof(IChangedHandler))] public interface IChat { //Opens a new session when executed [OperationContract(IsOneWay=false, IsInitiating = true)] void Subscribe(string inName); //Close the current session bound to the current client [OperationContract(IsOneWay = false, IsTerminating = true)] void Unsubscribe(); //Lets the client post a message [OperationContract(IsOneWay = true)] void publishNewMessage(string inMessage, string inName); } /// /// The interface that clients must implement /// public interface IChangedHandler { [OperationContract(IsOneWay = true)] void changed(string newMessage); } /// /// A singelton object of the chat class to be able to subscribe clients /// [ServiceBehavior(InstanceContextMode=InstanceContextMode.Single)] public class chat : IChat { private List mSubscribers = new List(); public chat() { } public void Subscribe(string inName) { mSubscribers.Add(OperationContext.Current.GetCallbackChannel()); } public void Unsubscribe() { IChangedHandler caller = OperationContext.Current.GetCallbackChannel(); foreach (IChangedHandler ch in mSubscribers) { if (ch == caller) { mSubscribers.Remove(ch); break; } } } public void publishNewMessage(string inMessage, string inName) { int nIndex = 0; try { foreach (IChangedHandler ch in mSubscribers) { ch.changed(inMessage); nIndex++; } } catch (Exception ex) { mSubscr