using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

namespace Service.Interface
{
 [ServiceContract(CallbackContract = typeof(ICallBack))]
 public interface INoticeOperator
 {
 [OperationContract]
 void Register(String id);

 [OperationContract]
 void UnRegister(String id);

 [OperationContract]
 void SendMessage(String from, String to, String message);
 }
} 

 using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

namespace Service.Interface
{
 public interface ICallBack
 {
 [OperationContract(IsOneWay = true)]
 void Notice(String message);
 }
} 

using Service.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Models
{
 public class Client
 {
 public String Id { get; set; }

 public ICallBack CallBack { get; set; }
 }
} 

 using Models;
using Service.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

namespace Service
{
 public class NoticeOperator : INoticeOperator
 {
 private static List<Client> clientList = new List<Client>();

 public void Register(string id)
 {
  Console.WriteLine("register:" + id);

  ICallBack callBack = OperationContext.Current.GetCallbackChannel<ICallBack>();
  clientList.Add(new Client() { Id = id, CallBack = callBack });
 }

 public void UnRegister(string id)
 {
  Console.WriteLine("unRegister:" + id);

  Client client = clientList.Find(c => c.Id == id);
  if (client != null)
  {
  clientList.Remove(client);
  }
 }

 public void SendMessage(string from, string to, string message)
 {
  Client client = clientList.Find(c => c.Id == to);
  if (client != null)
  {
  String longMessage = String.Format("message from {0} to {1} at {2} : {3}", from, to, DateTime.Now.ToString("HH:mm:ss"), message);
  Console.WriteLine(longMessage);
  client.CallBack.Notice(longMessage);
  }
 }
 }
} 

using Service;
using Service.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.Text;
using System.Threading.Tasks;

namespace Hosting
{
 class Program
 {
 static void Main(string[] args)
 {
  using (ServiceHost host = new ServiceHost(typeof(NoticeOperator)))
  {
  host.AddServiceEndpoint(typeof(INoticeOperator), new NetTcpBinding(), "net.tcp://127.0.0.1:9527/NoticeOperator");

  host.Opened += (s, e) => Console.WriteLine("service is running...");
  host.Open();
  Console.ReadLine();
  }
 }
 }
} 

using Service.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Test
{
 class CallBack : ICallBack
 {
 public void Notice(string message)
 {
  Console.WriteLine(message);
 }
 }
} 

 using Service.Interface;
using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

namespace Test
{
 class Program
 {
 static void Main(string[] args)
 {
  InstanceContext context = new InstanceContext(new CallBack());
  using (ChannelFactory<INoticeOperator> factory = new DuplexChannelFactory<INoticeOperator>(context, new NetTcpBinding(), "net.tcp://127.0.0.1:9527/NoticeOperator"))
  {
  INoticeOperator proxy = factory.CreateChannel();

  String selfId = args[0];
  String friendId = args[1];

  proxy.Register(selfId);
  Console.WriteLine("----------Register------------");

  while(true)
  {
   String message = Console.ReadLine();
   if (message == "q")
   {
   proxy.UnRegister(selfId);
   break;
   }
   else
   {
   proxy.SendMessage(selfId, friendId, message);
   }
  }
  }
 }
 }
}