服务契约（双工契约的服务器与客户端实现案例）

1、定义服务器端

     代码;

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


 namespace Contract
 {
     [ServiceContract(CallbackContract=typeof(IClientCallback))]
     public interface IServerStock
     {
         [OperationContract(IsOneWay = true)]
         void RegisterForUpdates(string ticker);
     }


     public interface IClientCallback
     {
         [OperationContract(IsOneWay = true)]
         void PriceUpdate(string ticker, double price);
     }


     public class ServerStock : IServerStock
     {
         //This is NOT a good notification algorithm as it's creating
         //one thread per client. It should be inverted so it's creating
         //one thread per ticker instead.
         public void RegisterForUpdates(string ticker)
         {
             Update bgWorker = new Update();
             bgWorker.callback = OperationContext.Current.GetCallbackChannel<IClientCallback>();
             Thread t = new Thread(new ThreadStart(bgWorker.SendUpdateToClient));
             t.IsBackground = true;
             t.Start();
         }
     }
     public class Update
     {
         public IClientCallback callback = null;
         public void SendUpdateToClient()
         {
             Random p = new Random();
             for (int i = 0; i < 10; i++)
             {
                 Thread.Sleep(5000); //updates occurs somewhere
                 try
                 {
                     callback.PriceUpdate("msft", 100.00 + p.NextDouble());
                 }
                 catch (Exception ex)
                 {
                     Console.WriteLine("Error sendinig cache to client:{0}", ex.Message);
                 }
             }
         }
     }
 }

    配置文件：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.serviceModel>
    <services>
      <service behaviorConfiguration="MEXServiceTypeBehavior" name="WCFTest.ServerStock">
        <endpoint address="" binding="wsDualHttpBinding" contract="WCFTest.IServerStock" />
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
            <add baseAddress="http://DL00549-990:8000" />
          </baseAddresses>
        </host>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="MEXServiceTypeBehavior">
          <serviceMetadata httpGetEnabled="true"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>
</configuration>

2、定义客户端

namespace
   Client
{
    
  public
   
  class
   CallbackHandler : IServerStockCallback
    {
        
  static
   InstanceContext site 
  =
  
            
  new
   InstanceContext(
  new
   CallbackHandler());
        
  static
   ServerStockClient proxy 
  =
   
  new
   ServerStockClient(site);
        
  public
   
  void
   PriceUpdate(
  string
   ticker, 
  double
   price)
        {
            Console.WriteLine(
  "
  Received alert at : {0}. {1}:{2}
  "
  , 
 
                System.DateTime.Now, ticker, price);
        }

        
  class
   Program
        {
            
  static
   
  void
   Main(
  string
  [] args)
            {
                proxy.RegisterForUpdates(
  "
  MSFT
  "
  );
                Console.WriteLine(
  "
  Press Enter or any key to exit
  "
  );
                Console.ReadLine();
            }
        }
    }
}