（转）贾君鹏你妈妈喊你回家吃饭利用WCF的Duplex推送消息

原文地址：http://www.cnblogs.com/xiaozhuang/archive/2009/07/22/1528712.html

有点标题党了，最近因工作需要，想利用WCF的Duplex服务向Winform程序推送消息，写了个示例，主要参考了artech的相关文章和其他一些利用WCF向SilverLight客户端推送消息的文章。
先看运行效果：在网页中发送消息【如图】，Winform端接收到消息

先建立两个项目，一个WebForm 项目和一个WinForm项目，并在项目下建立好各自需要的文件

SendMessage.aspx 是发送消息的Web页面
ISendMessageService.cs 和 SendMessageService.svc用来实现WCF的Duplex服务
GetMessageForm.cs 是接收消息的Winform窗口
当然，还需要建立一个消息实体文件：MessageEntity.cs,为简单起见，只给他定义一个属性。

[DataContract]
    public class MessageEntity
    {
        [DataMember]
        public string Content { get; set; }
    }

基本原理是消息发送的页面将要发送的消息列表保存在全局缓存中，在WCF服务中取得要发送的消息推送

到Winform端，SendMessage.aspx的代码如下：

protected void btnSend_Click(object sender, EventArgs e)
        {
            MessageEntity message = new MessageEntity();
            message.Content = txtMessageContent.Text;

            List<MessageEntity> messageList = HttpRuntime.Cache["MessageEntityList"] as List<MessageEntity>;
            if (messageList == null)
            {
                messageList = new List<MessageEntity>();
                messageList.Add(message);
                HttpRuntime.Cache.Add("MessageEntityList", messageList, null, System.Web.Caching.Cache.NoAbsoluteExpiration, System.Web.Caching.Cache.NoSlidingExpiration, System.Web.Caching.CacheItemPriority.Default, null);
            }
            else
            {
                messageList.Add(message);
                HttpRuntime.Cache["MessageEntityList"] = messageList;
            }

            lbCacheCount.Text = messageList.Count.ToString();
        }

ISendMessageService.cs 用来定义消息接收接口和回调接口

[ServiceContract(CallbackContract = typeof(ISendMessageServiceCallBack))]
    public interface ISendMessageService
    {
        [OperationContract(IsOneWay = true)]
        void GetMessage();
    }

    public interface ISendMessageServiceCallBack
    {
        [OperationContract(IsOneWay = true)]
        void ReceiveMessage(MessageEntity messageEntity);
    }

SendMessageService.svc.cs 用来实现将缓存中的消息列表一个一个的推送出去，采用Timer类每2-5秒钟推送一次：

[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple)]
    public class SendMessageService : ISendMessageService
    {
        ISendMessageServiceCallBack callback;
        Timer heartTimer;
        Random random = new Random();

        #region ISendMessageService 成员

        public void GetMessage()
        {
            callback = OperationContext.Current.GetCallbackChannel<ISendMessageServiceCallBack>();
            heartTimer = new Timer(new TimerCallback(heartTimer_Elapsed), null, 3000, Timeout.Infinite);
        }

        #endregion

        private void heartTimer_Elapsed(object data)
        {
            List<MessageEntity> messageList = HttpRuntime.Cache["MessageEntityList"] as List<MessageEntity>;
            if (messageList != null && messageList.Count > 0)
            {
                MessageEntity message = messageList[0];
                messageList.Remove(message);
                HttpRuntime.Cache["MessageEntityList"] = messageList;
                callback.ReceiveMessage(message);
            }
            int interval = random.Next(2000, 5000);
            heartTimer.Change(interval, Timeout.Infinite);
        }
    }

记得修改Web.Config中EndPoint Binding 为wsDualHttpBinding ，这样才支持Duplex服务

<service behaviorConfiguration="WebApp.SendMessageServiceBehavior" name="WebApp.SendMessageService">
                <endpoint address="" binding="wsDualHttpBinding" contract="WebApp.ISendMessageService">
                    <identity>
                        <dns value="localhost"/>
                    </identity>
                </endpoint>
                <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
            </service>

WebApp项目的工作已经完成，若没有错误可在浏览器中看到该WCF服务已创建，拷贝该服务的地址，例如在我本机上是：http://localhost:1407/SendMessageService.svc，并在WinApp项目中增加该服务的引用
GetMessageForm.cs 实现如下：

public partial class GetMessageForm : Form,ISendMessageServiceCallback
    {
        SendMessageServiceClient client;

        public GetMessageForm()
        {
            InitializeComponent();
            client = new SendMessageServiceClient(new System.ServiceModel.InstanceContext(this));
        }

        private void btnStartGet_Click(object sender, EventArgs e)
        {
            client.GetMessage();
        }

        private delegate void UpdateListBoxDelegate(string Message);
        private void UpdateListBox(string message)
        {
            this.listbMessage.Items.Add(message);
            listbMessage.SelectedIndex = listbMessage.Items.Count - 1;
        }
        #region ISendMessageServiceCallback 成员

        public void ReceiveMessage(MessageEntity messageEntity)
        {
            if (true == listbMessage.InvokeRequired)
            {
                listbMessage.Invoke(new UpdateListBoxDelegate(UpdateListBox), messageEntity.Content);
            }
            else
            {
                UpdateListBox(messageEntity.Content);
            }
        }

        #endregion

    }

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