Mediator Interface (IChatMediator):?

• The IChatMediator interface defines two key operations:

■ SendMessage(string message, User user): Sends a

message from a user to all other registered users.

■ RegisterUser(User user): Registers users with the mediator so

they can send and receive messages.

public interface IChatMediator
{

void SendMessage(string message, User user);

void RegisterUser(User user);

}