ChatService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ChatClient
{
    public class ChatService : IChatService
    {
        public delegate void UserJoined(string name);
        public delegate void UserSendMessage(string name, string message);
        public delegate void UserLeft(string name);

        public event UserJoined NewJoin;
        public event UserSendMessage MessageSent;
        public event UserLeft RemoveUser;

        public string UserName { get; set; }

        public ChatService()
        {
        }

        public void Join(string memberName)
        {
            if (NewJoin != null)
            {
                NewJoin(memberName);
            }
        }

        public void Leave(string memberName)
        {
            if (RemoveUser != null)
            {
                RemoveUser(memberName);
            }
        }

        public void SendMessage(string memberName, string message)
        {
            if (MessageSent != null)
            {
                MessageSent(memberName, message);
            }
        }
    }
}