wcf 双工通讯

但在双向操作模式中，不但客户端可以向服务器发送请求，服务器也可以主动向客户端广播消息(也就是回调客户端中的方法)。在WCF中，不是所有的绑定都可以实现双向操作模式的，比如http协议，它本身就是基于请求-回复的传输模式，所以本质上是实现不了双向操作的。但WCF提供了 WSDualHttpBinding协议让我们在http上实现了双向操作。其实WSDualHttpBinding并没有违反http单向传输的本质, 它实际上是创建两个了通道，一个用于客户端向服务器请求，一个用于服务器向客户端广播，间接实现了双向操作。但《WCF服务编程》书上有说，WSDualHttpBinding无法穿越客户端与服务器的重重障碍，所以不赞成使用WSDualHttpBinding来实现双向操作。

第一步

新建一个windows应用程序，取名Host

第2步：建立接口，IMessageService

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

namespace Host
{
    //和单向操作相比，我们会发现服务契约上多了一行代码：[ServiceContract(CallbackContract = typeof(ICallBack))]
    [ServiceContract(CallbackContract = typeof(ICallBack))]
    public interface IMessageService
    {
        [OperationContract]
        void RegisterMes();

        [OperationContract]
        int SendToAll(string name, string msg);
        /// <summary>
        /// 文件上传
        /// </summary>
        /// <param name="data">字节数组</param>
        /// <param name="suffix">文件后缀名</param>
        /// <returns></returns>
        [OperationContract]
        int SentFile(byte[] data, string suffix);
    }

    public interface ICallBack
    {
        [OperationContract(IsOneWay = true)]
        void SendMessage(string name, string msg);

        [OperationContract(IsOneWay = true)]
        void Show();
    }
}

这时候引用 wcf组件

第 3步建立实现 MessageService

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

namespace Host
{
    [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
    public class MessageService : IMessageService, IDisposable
    {
        public static List<ICallBack> CallBackList
        {
            get;
            set;
        }

        public MessageService()
        {
            CallBackList = new List<ICallBack>();
        }

        public void RegisterMes()
        {
            var callback = OperationContext.Current.GetCallbackChannel<ICallBack>();
            string sessionid = OperationContext.Current.SessionId;

            Form1.fm1.listLine.Items.Add(sessionid);//服务端显示客户端的SessionId

            //OperationContext.Current.Channel.Closing +=
            //    delegate
            //    {
            //        lock (CallBackList)
            //        {
            //            CallBackList.Remove(callback);
            //        }
            //    };

            OperationContext.Current.Channel.Closing += new EventHandler(Channel_Closing);
            CallBackList.Add(callback);
        }

        void Channel_Closing(object sender, EventArgs e)
        {
            lock (CallBackList)
            {
                CallBackList.Remove((ICallBack)sender);
            }
        }

        public void Dispose()
        {
            CallBackList.Clear();
        }

        public int SendToAll(string name, string msg)
        {
            var list = Host.MessageService.CallBackList;
            if (list == null || list.Count == 0)
                return 0;
            lock (list)
            {
                Task.Factory.StartNew(new Action(() =>
                {
                    foreach (var client in list)
                    {
                        client.SendMessage(name, msg);

                    }
                }));
            }
            return 1;
        }

        /// <summary>
        /// 文件上传
        /// </summary>
        /// <param name="data">字节数组</param>
        /// <param name="suffix">文件后缀名</param>
        /// <returns></returns>
        public int SentFile(byte[] data, string suffix)
        {
            DateTime dt = DateTime.Now;
            string filename = string.Format("{0:yyyyMMddHHmmssffff}", dt);
            File.WriteAllBytes(filename+suffix, data);
            return 0;
        }
    }
}

第4步配置 Appconfig

右键Appconfig 点击编辑wcf配置进入元素浏览器（我把这个理解成可视化配置），这样免去程序员手敲代码的麻烦。

上几张图

看到3张图没，新建了一个服务，添加了2个终结点

app.config生产代码

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.web>
    <compilation debug="true"/>
  </system.web>
  <system.serviceModel>
    <services>
      <service name="Host.MessageService">
        <endpoint address="" binding="netTcpBinding" bindingConfiguration="NetTcpBinding_IMessageService" contract="Host.IMessageService">
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
        <host>
          <baseAddresses>
            <add baseAddress="net.tcp://192.168.2.23:9999/Host/"/>
            <add baseAddress="http://192.168.2.23:9998/Host"/>
          </baseAddresses>
        </host>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <serviceMetadata httpGetEnabled="True"/>
          <serviceDebug includeExceptionDetailInFaults="False"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <bindings>
      <netTcpBinding>
        <binding name="NetTcpBinding_IMessageService" maxBufferSize="1024000000" maxReceivedMessageSize="1024000000" sendTimeout="00:00:30" transferMode="Buffered">

          <security mode="None">

            <transport clientCredentialType="Windows" />

            <message clientCredentialType="Windows" />

          </security>
        </binding>
      </netTcpBinding>
    </bindings>
  </system.serviceModel>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
  </startup>
</configuration>

这个说下wcf 之 abc

Address: 每一个WCF的Service都有一个唯一的地址。这个地址给出了Service的地址和传输协议(Transport Protocol)
Binding:通信(Communication)的方式很多,同步的request/reply模式，非同步的fire-and- forget模式。消息可以单向或者双向的发送接收，可以立即发送或者把它放入到某一个队列中再处理。所供选择的传输协议也有Http, Tcp,P2P,IPC等。当要考虑Client/Server如何进行通讯的时候，除了考虑以上提到的几点之外，还有其它很多需要考虑的因素，如安全，性能等。因此，简单来说，Binding只不过是微软提供的一组考虑比较周全、常用的封装好的通信方式。
Contract:Contract描述了Service能提供的各种服务。Contract有四种，包括Service Contract, Data Contract, Fault Contract和Message Contract

第5步建立客户端取名 Client 添加 System.ServiceModel引用，添加wcf引用

这里强调一下wcf引用怎么加入项目里，打开wcf服务端生成的bin文件，运行Host.exe文件

这时候 http://192.168.2.23:9998/Host 就可以访问了，取名叫WcfSvc

引用wcf服务的时候你发现客户端 app.config配置文件已经生成了

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <system.serviceModel>
        <bindings>
            <netTcpBinding>
                <binding name="NetTcpBinding_IMessageService">
                    <security mode="None" />
                </binding>
            </netTcpBinding>
        </bindings>
        <client>
            <endpoint address="net.tcp://192.168.2.23:9999/Host/" binding="netTcpBinding"
                bindingConfiguration="NetTcpBinding_IMessageService" contract="WcfSvc.IMessageService"
                name="NetTcpBinding_IMessageService" />
        </client>
    </system.serviceModel>
</configuration>

在Client工程里新建 MyCallBack 类回调服务端方法

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

namespace Client
{
    public class MyCallBack : WcfSvc.IMessageServiceCallback
    {

        public long count = 0;
        public void SendMessage(string name, string msg)
        {
            System.Threading.Interlocked.Increment(ref count);

            Form1.f.listMessage.Items.Add(string.Format("{0}:{1}:{2}", name, msg, count));
            Form1.f.txtreceiving.Invoke(new Action(() =>
            {
                Form1.f.txtreceiving.Text = count.ToString();
            }));


        }


        public void Show()
        {
            Form1.f.listMessage.Invoke(new Action(() =>
            {
                Form1.f.listMessage.Items.Add("show方法调用了");
            }));
        }

    }
}

这时候双工通讯搭建完毕，再来设计UI页面

这里设置ui控件有个技巧：默认控件是私有属性，我把上线这边文本框改成 public,让他接受外面访问。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Windows.Forms;

namespace Host
{
    public partial class Form1 : Form
    {
        public static Form1 fm1;
        private ServiceHost _host = null;

        public Form1()
        {
            InitializeComponent();

            //构造函数初始化加载
            fm1 =this;
            CheckForIllegalCrossThreadCalls = false;
            BindHost();
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            BindHost();
        }

        void BindHost()
        {
            try
            {
                _host = new ServiceHost(typeof(Host.MessageService));
                _host.Open();
                lbService.Text = string.Format("服务开启：{0}", DateTime.Now.ToString());
            }
            catch (Exception ex)
            {
                ShowMessage(ex.Message);
            }
        }

        private void btnsend_Click(object sender, EventArgs e)
        {//发送内容
            #region 备用
            if (fm1 != null)
            {
                lock (MessageService.CallBackList)
                {
                    foreach (ICallBack callback in MessageService.CallBackList)
                    {
                        callback.SendMessage("服务器发送: ", txtMsg.Text);
                    }

                }
            }
            #endregion

        }

        /// <summary>
        /// (公用的)信息显示
        /// </summary>
        /// <param name="msg">消息内容</param>
        private void ShowMessage(string msg)
        {
            this.lbMessage.Text = msg;
            this.lbMessage.Visible = true;
        }
    }
}

画客户端页面

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.ServiceModel;
using System.Threading.Tasks;
using System.IO;

namespace Client
{
    public partial class Form1 : Form
    {
        public static Form1 f;

        public Form1()
        {
            InitializeComponent();

            f = this;
            CheckForIllegalCrossThreadCalls = false;
           
        }
        WcfSvc.MessageServiceClient svc;

        private void Form1_Load(object sender, EventArgs e)
        {//页面初始化
            //Online();

            var client = new MyCallBack();
            var ctx = new InstanceContext(client);
            svc = new WcfSvc.MessageServiceClient(ctx);
            svc.RegisterMes();
        }

        private void button1_Click(object sender, EventArgs e)
        {//停止
            isRun = false;
        }


        void ShowMessage(string msg)
        {
            this.lbError.Text = msg;
            this.lbError.Visible = true;
        }

        Task t;
        int sleeptime = 100;
        bool isRun = true;

        private void btnSend_Click(object sender, EventArgs e)
        {//发送
            isRun = true;
            sleeptime = int.Parse(txtNum.Text);
            t = Task.Factory.StartNew(delegate
            {
                while (true)
                {
                    if (isRun)
                    {
                        svc.SendToAll(txtUserName.Text, txtSendMessage.Text);
                        System.Threading.Thread.Sleep(sleeptime);
                    }
                    else
                    {
                        break;
                    }

                }
            });
        }

        private void btnclear_Click(object sender, EventArgs e)
        {//清屏
            this.listMessage.Items.Clear();
        }

        private void btnUpload_Click(object sender, EventArgs e)
        {//文件上传
            using (OpenFileDialog ofd = new OpenFileDialog())
            {
                if (ofd.ShowDialog() == DialogResult.OK)
                {
                    //FileStream fs = new FileStream(ofd.FileName, FileMode.Open, FileAccess.Read);
                    byte[] data = File.ReadAllBytes(ofd.FileName);
                    int r = svc.SentFile(data, Path.GetExtension(ofd.FileName));
                    if (r == 0)
                    {
                        MessageBox.Show("发送完毕");
                    }
                }
            }
        }


    }
}

上几张双工效果图，服务实现 “有图有真相”。

服务端向客户端发送请求。

客户端向客户端发送请求

分享一下我的源码，有什么建议的朋友可以留言给我，相互讨论，相互学习。

大家可以把双工通讯理解成 “礼上往来”的通讯。

源码下载