[WCF]wsDualHttpBinding绑定问题

[qq22345111]

System.Configuration.ConfigurationErrorsException: 
无法找到配置绑定扩展“system.serviceModel/bindings/wsDualHttpBinding”。
请验证此绑定扩展是否已在 system.serviceModel/extensions/bindingExtensions 中正确注册以及是否拼写正确。

APP.Config配置

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.web>
    <compilation debug="true" />
  </system.web>
  <system.serviceModel>
    <services>
      <service name="Wrox.ProCSharp.MessageService">
        <host>
          <baseAddresses>
            <add baseAddress = "http://localhost:8732/Design_Time_Addresses/MessageService/Service1/" />
          </baseAddresses>
        </host>
        <endpoint address ="" binding="wsdualHttpBinding" contract="Wrox.ProCSharp.WCF.IMyMessage">
          <identity>
            <dns value="localhost"/>
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <serviceMetadata httpGetEnabled="True"/>
          <serviceDebug includeExceptionDetailInFaults="False" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>
</configuration>

[qq22345111]

接口定义如下：

namespace Wrox.ProCSharp.WCF
{

    public interface IMyMessageCallback
    {
        [OperationContract(IsOneWay = true)]
        void OnCallback(string message);
    }

    [ServiceContract(CallbackContract = typeof(IMyMessageCallback))]
    public interface IMyMessage
    {
        [OperationContract]
        void MessageToServer(string message);
    }
}

实现类代码如下：

namespace Wrox.ProCSharp.WCF
{
   public class MessageService : IMyMessage
   {
      public void MessageToServer(string message)
      {
         Console.WriteLine("message from the client: {0}", message);
         IMyMessageCallback callback =
               OperationContext.Current.
                     GetCallbackChannel<IMyMessageCallback>();

         callback.OnCallback("message from the server");

         Task.Factory.StartNew(new Action<object>(TaskCallback), callback);
         // new Thread(ThreadCallback).Start(callback);
      }
      private void TaskCallback(object callback)
      {
          IMyMessageCallback messageCallback = callback as IMyMessageCallback;
          for (int i = 0; i < 10; i++)
          {
              messageCallback.OnCallback("message " + i.ToString()+"来源于服务的消息!");
              Thread.Sleep(1000);
          }
      }
}