【转】利用WCF的双工通信

Silverlight与WCF之间的通信(2)利用WCF的双工通信“推送”给SL数据

作者：Leon Weng 来源：博客园发布时间：2010-06-19 23:43 阅读：2215 次原文链接 [收藏]

一，Duplex简介

上一个随笔记录了SL利用Timer定时去WCF上取数据再绑定到界面上的问题，今天尝试用了WCF的Duplex双工通信来做这个事情，也以这个例子来说明WCF中Duplex的使用。

双工通信的原理很简单，我们平时用的是客户端调用服务端的方法来获取数据，而Duplex是将客户端也当作了服务器，客户端上的方法也可以被调用，以聊天功能为例子，用户A连接到服务器后，之前的做法是客户端定时取数据，而Duplex是在服务端定时检测数据变化，如果发现了发送给A的信息，那么立即会调用客户端的方法来推送信息到A。

二，建立Duplex模式的WCF服务

这里以一个简单的聊天功能来说明，WCF提供了三个方法，连接到服务器方法，发送信息方法和接收信息方法。从服务契约上来说分为两个接口，分别是为客户端提供发送信息和开始聊天方法的IChatService接口和服务器调用客户端方法的IChatServiceCallBack接口

IChatService.cs文件

代码

namespace ChatWCF
{
     [ServiceContract(CallbackContract=typeof(IChatServiceCallBack))]//这里需要定义IChatService接口的回调接口IChatServiceCallBack
    public interface IChatService
    {
        [OperationContract]
        bool SendMessage(MessageInfo msg); //发送信息

        [OperationContract]
        bool LoginChat(string User,string Partner);//开始聊天模式
    }

    [ServiceContract]
    public interface IChatServiceCallBack //供服务端回调的接口
    {
        [OperationContract(IsOneWay=true)]
        void ReceiveMessages(List<MessageInfo> listMessages);//客户端被服务端回调后接收信息
    }
}

接下来需要实现这接口，IChatService.svc.cs

代码

namespace ChatWCF
{
     public class ChatService : IChatService
     {
        IChatServiceCallBack chatserviceCallBack;
        string _user;
        string _partner;
　　　　 Timer timer;
//开始聊天
public bool LoginChat(string User, string Partner)

        {
            try
            {
                chatserviceCallBack = OperationContext.Current.GetCallbackChannel<IChatServiceCallBack>();
                _user = User;
                _partner = Partner;

                timer = new Timer(new TimerCallback(CheckMessages), this, 100, 100);

                return true;
            }
            catch(Exception ex)
            {
                return false;
            }
        }
//检查消息并回调客户端接收此消息，此处是回调的重点
        private void CheckMessages(object o)

        {
            chatserviceCallBack.ReceiveMessages(GetMessages(_user,_partner));
        }

//发送信息
public bool SendMessage(MessageInfo msg)
{
                [将MessageInfo写入数据库...]
}

//检测数据库
private List<MessageInfo> GetMessages(string User, string Partner)
{
            List<MessageInfo> listMsg = new List<MessageInfo>();

[检测数据库并返回检测到的MessageInfo...]

            return listMsg;
}

//执行简单的SQL语句
private DataSet ExcuteSQL(string strSql)
       {
            string strServer = "server=LEON-PC\\sql2005;database=jplan;uid=sa;pwd=sa;";
            SqlConnection con = new SqlConnection(strServer);
            con.Open();
            SqlDataAdapter dataAdapter = new SqlDataAdapter(strSql, con);
            DataSet ds = new DataSet();
            dataAdapter.Fill(ds);
            con.Close();

            return ds;
        }
    }
}

这里需要注意一点的是这个WCF是建立在Duplex基础上的，所以在wcf的项目中需要添加一个程序集：

Assembly System.ServiceModel.PollingDuplex
C:\Program Files\Microsoft SDKs\Silverlight\v4.0\Libraries\Server\System.ServiceModel.PollingDuplex.dll

接下来需要对Web.config进行配置，主要是ServiceModel节点：

代码

<system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior name="ChatWCF.ChatBehavior">
          <serviceMetadata httpGetEnabled="true" />
          <serviceDebug includeExceptionDetailInFaults="false" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <services>
      <service behaviorConfiguration="ChatWCF.ChatBehavior" name="ChatWCF.ChatService">
        <endpoint
           address=""
           binding="pollingDuplexHttpBinding"
           bindingConfiguration="multipleMessagesPerPollPollingDuplexHttpBinding"
           contract="ChatWCF.IChatService">
        </endpoint>
        <endpoint
            address="mex"
            binding="mexHttpBinding"
            contract="IMetadataExchange"/>
      </service>
    </services>
    <extensions>
      <bindingExtensions>
        <add name=
            "pollingDuplexHttpBinding"
            type="System.ServiceModel.Configuration.PollingDuplexHttpBindingCollectionElement,System.ServiceModel.PollingDuplex, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
      </bindingExtensions>
    </extensions>

    <bindings>
      <pollingDuplexHttpBinding>
        <binding name="multipleMessagesPerPollPollingDuplexHttpBinding"
                 duplexMode="MultipleMessagesPerPoll"
                 maxOutputDelay="00:00:07"/>
      </pollingDuplexHttpBinding>
    </bindings>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
</system.serviceModel>

如果您的WCF服务是一个单独的站点，而客户端是SL的话，鉴于SL的安全性考虑不支持跨域访问，那么就需要在WCF的根目录下放置一个XML策略文件，文件名为

clientaccesspolicy.xml：

代码

<?xml version="1.0" encoding="utf-8"?>
<access-policy>
<cross-domain-access>
    <policy>
      <allow-from http-request-headers="SOAPAction">
        <domain uri="*"/>
      </allow-from>
      <grant-to>
        <resource path="/" include-subpaths="true"/>
      </grant-to>
    </policy>
</cross-domain-access>
</access-policy>

如果您的配置和代码书写正确，浏览一下WCF服务会发现下图，说明服务已经正确host到VS的轻量级IIS上了

三，Silverlight跨域访问WCF的Duplex服务

先建立一个单独的project，silverlight app，当然还是需要先引用WCF服务的：

新建一个SL文件，Chat.xaml代码，包括了一个发送消息窗口和一个显示聊天信息的窗口，这个聊天的窗口从普通HTML街面上接收两个参数，即user和partner互为聊天对象。

代码

后台代码中需要从HTML中接收聊天对象:

代码

namespace ChatSL
{
    public partial class Chat : UserControl
    {
        string user;
        string partner;

        EndpointAddress address ;
        PollingDuplexHttpBinding binding;
        ChatService.ChatServiceClient proxy;

        public Chat()
        {
            InitializeComponent();

            this.Loaded+=new RoutedEventHandler(Chat_Loaded);
            this.txtMessage.KeyDown += new KeyEventHandler(KeyDownProcess);
            this.btnSend.Click += new RoutedEventHandler(btnSend_Click);
            this.btnClose.Click += new RoutedEventHandler(btnClose_Click);
        }

        void Chat_Loaded(object sender,RoutedEventArgs e)
        {
            HtmlElement element;
            element = HtmlPage.Document.GetElementById("lbluser");
            this.txtMe.Text = element.GetAttribute("innerText");
            element = HtmlPage.Document.GetElementById("lblpartner");
            this.txtPartner.Text = element.GetAttribute("innerText");

            user = this.txtMe.Text;
            partner = this.txtPartner.Text;

            LogIn();
        }
//向服务器示意上线
        private void LogIn()
        {
            address = new EndpointAddress("http://localhost:32662/ChatService.svc%22);
            binding = new PollingDuplexHttpBinding(PollingDuplexMode.MultipleMessagesPerPoll);
            proxy = new ChatService.ChatServiceClient(binding,address);
            proxy.ReceiveMessagesReceived+=new EventHandler<ChatService.ReceiveMessagesReceivedEventArgs>(proxy_ReceiveMessagesReceived);
            proxy.LoginChatAsync(user, partner);
        }

        #region 绑定数据
        void proxy_ReceiveMessagesReceived(object sender,ChatService.ReceiveMessagesReceivedEventArgs e)
        {
            this.listMsgs.ItemsSource = e.listMessages;
        }

        private void SetDataSource()
        {

        }
        #endregion

        #region 键盘事件
        protected void KeyDownProcess(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.Enter)
            {
                SendMessage();
            }
        }
        #endregion

        #region 发送信息
        private void btnSend_Click(object sender, RoutedEventArgs e)
        {
            SendMessage();
        }
        private void SendMessage()
        {
            if (this.txtMessage.Text == "")
            {
                MessageBox.Show("请输入信息！");
                return;
            }

            ChatService.MessageInfo message = new ChatService.MessageInfo();
            message.ID = Guid.NewGuid().ToString();
            message.Receipt = 0;
            message.ReceiveMode = "user";
            message.ReceiveOrgan = "";
            message.ReceiveUser = this.txtPartner.Text;
            message.Message = this.txtMessage.Text;
            message.Sender = this.txtMe.Text;
            message.SendTime = DateTime.Now;
            message.Source = "web";
            message.State = 0;
            message.Title = this.txtMessage.Text;

            proxy = new ChatService.ChatServiceClient(binding, address);
            proxy.SendMessageCompleted += new EventHandler<ChatService.SendMessageCompletedEventArgs>(SendMessageComleted);
            proxy.SendMessageAsync(message);

            this.txtMessage.Text = "";
        }
        void SendMessageComleted(object sender, ChatService.SendMessageCompletedEventArgs e)
        {
            if (e.Error == null)
            {
                //MessageBox.Show(e.Result.ToString());
            }
        }
        #endregion

        #region 关闭窗口
        private void btnClose_Click(object sender, EventArgs e)
        {

        }
        #endregion
    }
}

效果图：

源代码（包含视频部分）：https://files.cnblogs.com/wengyuli/Chat_%e5%8f%8c%e5%b7%a5http.7z

posted @ 2011-06-08 19:02 牛小浩阅读(509) 评论(0) 编辑收藏举报

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