WCF回调实现

这两天翻了很多关于回调资料，后来才恍然大悟，贴上来说下解决方案。

1. 回调接口声明

    public interface ICallback    {        [OperationContract(IsOneWay = true)] // 回调操作也必须One Way          void CallbackToClient(DateTime timestamp, string message);    }

2.回调使用

/// <summary>    /// 设置服务行为为单例模式,即所有客户端共享一个服务实例    /// </summary>    [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)]    public class MyTagService : IService    {

           static List<ICallback> m_Callbacks = new List<ICallback>();

           public void AddMessage(string message)        {            m_Callbacks.ForEach(callback =>            {                if (((ICommunicationObject)callback).State == CommunicationState.Opened)                    callback.CallbackToClient(DateTime.Now, message);                else                    m_Callbacks.Remove(callback);            });

         }

       /// <summary>        /// read from plc and update local value        /// </summary>        /// <param name="plcTag">需要读取PLC的变量</param>        /// <returns>无</returns>        public string Read_PLC_Tag(PLCTag tag)        {            string value=plc.TagValue(tag);            if (ServerMessageGot != null)            {                ServerMessageGot(this, new MessageReceiveEventArgs(DateTime.Now,tag.Address.ToString() + "-" + tag.DataSize.ToString() + "-" + value.ToString()));            }            AddMessage(tag.Address.ToString() + "-" + tag.DataSize.ToString() + "-" + value.ToString());     //回调                        return value;        }

    }

3. 回调事件

///<summary>      ///实现回调接口      ///</summary>       [CallbackBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, UseSynchronizationContext = false)]    public class MyCallback : ICallback    {        /// <summary>          // 回调后触发该事件，用于通知客户端          /// </summary>           public event EventHandler<MessageReceiveEventArgs> ValueCallbacked = delegate { };        // 因为该方法是由服务器调用的          // 如果希望在客户端能即时作出响应          // 应当使用事件          public void CallbackToClient(DateTime timestamp, string message)        {            MessageReceiveEventArgs e = new MessageReceiveEventArgs(timestamp,message);            if (this.ValueCallbacked != null)            {                this.ValueCallbacked(this, e);            }        }    }

4.客户端回调

 public class Client     {        IService ClientChanel;        DuplexChannelFactory<IService> channelFactory;        MyCallback Callback = new MyCallback();                /// <summary>        /// 服务端对客户端的消息通知        /// </summary>        public event EventHandler<MessageReceiveEventArgs> ServerMessageReceived = delegate { };        public Client(string ServerName)        {            NetTcpBinding binding = new NetTcpBinding();            binding.Security.Mode = SecurityMode.None;            InstanceContext instanceContext = new InstanceContext(Callback);            channelFactory = new DuplexChannelFactory<IService>(instanceContext, binding, new EndpointAddress("net.tcp://" + ServerName + ":2970/PLCTagServices/"));            ClientChanel=channelFactory.CreateChannel();            ClientChanel.Subscribe();            channelFactory.Faulted += new EventHandler(channelFactory_Faulted);                        Callback.ValueCallbacked+=new EventHandler<MessageReceiveEventArgs>(Callback_ValueCallbacked);        }                void Callback_ValueCallbacked(object sender,MessageReceiveEventArgs e)        {            ServerMessageReceived(this, e);        }

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