在使用 Rmoting 时候，服务器端如下配置：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.runtime.remoting>
<application>
<service>
<wellknown mode="Singleton"
type="MathLibrary.SimpleMath,MathLibrary"
objectUri = "SimpleMath.rem"/>
</service>
<channels>
<channel ref="http">
<serverProviders>
<formatter ref="soap"/> </serverProviders>
</channel>
</channels>

</application>
</system.runtime.remoting>
</configuration>

当我在WEB浏览器上输入 ：http://localhost/MathService/SimpleMath.rem?wsdl 为什么不显示WSDL描述，出现异常：

System.ArgumentNullException: 调用 DispatchChannelSink 之前没有反序列化任何消息。
参数名: requestMsg
at System.Runtime.Remoting.Channels.DispatchChannelSink.ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)
at System.Runtime.Remoting.Channels.SoapServerFormatterSink.ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)
at System.Runtime.Remoting.Channels.Http.HttpHandlerTransportSink.HandleRequest(HttpContext context)
at System.Runtime.Remoting.Channels.Http.HttpRemotingHandler.InternalProcessRequest(HttpContext context)