使用 NetTcpBinding 进行双工通信 - ContractFilter 不匹配？

我正在使用 NetTcpBinding 在客户端和服务器之间打开双工通信通道方面取得缓慢而稳定的进展。 （仅供参考，你可以观察我的新手进度here and here!)

我现在正处于已成功连接到服务器的阶段，通过服务器的防火墙，客户端可以向服务器发出请求。

然而，从另一个方向来看，事情却并不那么令人高兴。在我自己的机器上测试时它工作正常，但是当通过互联网测试时，当我尝试从服务器端启动回调时，我收到错误：

The message with Action 'http://MyWebService/IWebService/HelloWorld' cannot be
processed at the receiver, 
due to a ContractFilter mismatch at the EndpointDispatcher. 
This may be because of either a contract mismatch (mismatched Actions between 
sender and receiver) 
or a binding/security mismatch between the sender and the receiver.  
Check that sender and receiver have the same contract and the same binding 
(including security requirements, e.g. Message, Transport, None).

以下是一些关键代码。一、网页界面：

[ServiceContract(Namespace = "http://MyWebService", SessionMode = SessionMode.Required, CallbackContract = typeof(ISiteServiceExternal))]
public interface IWebService {
  [OperationContract]
  void Register(long customerID);
}

public interface ISiteServiceExternal {
  [OperationContract]
  string HelloWorld();
}

下面是 IWebService 的实现：

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
class WebService : IWebService {
  void IWebService.Register(long customerID) {
    Console.WriteLine("customer {0} registering", customerID);
    var callbackService = OperationContext.Current.GetCallbackChannel<ISiteServiceExternal>();
    RegisterClient(customerID, callbackService);
    Console.WriteLine("customer {0} registered", customerID);
  }
}

然后，在客户端（我在摆弄这些属性时并不真正知道我在做什么）：

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, Namespace="http://MyWebService")]
class SiteServer : IWebServiceCallback {
  string IWebServiceCallback.HelloWorld() {
return "Hello World!";
  }
  ...
}

那么我在这里做错了什么？

EDIT:添加app.config代码。从服务器：

<system.serviceModel>
  <diagnostics>
    <messageLogging logMalformedMessages="true" logMessagesAtServiceLevel="true"
        logMessagesAtTransportLevel="true" logEntireMessage="true" maxMessagesToLog="1000" maxSizeOfMessageToLog="524288" />
  </diagnostics>
  <behaviors>
    <serviceBehaviors>
      <behavior name="mex">
        <serviceDebug includeExceptionDetailInFaults="true"/>
        <serviceMetadata/>
      </behavior>
    </serviceBehaviors>
  </behaviors>
  <services>
    <service name ="MyWebService.WebService" behaviorConfiguration="mex">
      <endpoint address="net.tcp://localhost:8000" binding="netTcpBinding" contract="MyWebService.IWebService"
                bindingConfiguration="TestBinding" name="MyEndPoint"></endpoint>
      <endpoint address ="mex"
                binding="mexTcpBinding"
                name="MEX"
                contract="IMetadataExchange"/>
      <host>
        <baseAddresses>
          <add baseAddress="net.tcp://localhost:8000"/>
        </baseAddresses>
      </host>
    </service>
  </services>
  <bindings>
    <netTcpBinding>
      <binding name="TestBinding" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" portSharingEnabled="false">
        <readerQuotas maxDepth="32" maxStringContentLength ="8192" maxArrayLength ="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384"/>
        <security mode="None"/>
      </binding>
    </netTcpBinding>
  </bindings>
</system.serviceModel>

在客户端：

<system.serviceModel>
  <bindings>
    <netTcpBinding>
      <binding name="MyEndPoint" closeTimeout="00:01:00" openTimeout="00:01:00"
          receiveTimeout="00:10:00" sendTimeout="00:01:00" transactionFlow="false"
          transferMode="Buffered" transactionProtocol="OleTransactions"
          hostNameComparisonMode="StrongWildcard" listenBacklog="10"
          maxBufferPoolSize="524288" maxBufferSize="65536" maxConnections="10"
          maxReceivedMessageSize="65536">
        <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384"
            maxBytesPerRead="4096" maxNameTableCharCount="16384" />
        <reliableSession ordered="true" inactivityTimeout="00:10:00"
            enabled="false" />
        <security mode="None">
          <transport clientCredentialType="Windows" protectionLevel="EncryptAndSign">
            <extendedProtectionPolicy policyEnforcement="Never" />
          </transport>
          <message clientCredentialType="Windows" />
        </security>
      </binding>
    </netTcpBinding>
  </bindings>
  <client>
    <endpoint address="net.tcp://mydomain.gotdns.com:8000/" binding="netTcpBinding"
        bindingConfiguration="MyEndPoint" contract="IWebService" name="MyEndPoint" />
  </client>
</system.serviceModel>

感谢@Allon Guralnek，他帮助我发现了问题所在：

在服务器端我有：

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
class WebService : IWebService { ... }

在客户端我有：

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, Namespace="http://MyWebService")]
class SiteServer : IWebServiceCallback { ... }

冲突发生在PerCall and PerSession。我刚刚将服务器端更改为PerSession，以及 - 休斯顿，我们起飞了！

现在，为了让它与安全性一起工作...请观看我的 WCF 学习曲线中下一个令人兴奋的部分！ :)