wcf - 请求 WCF 服务契约(Contract)时出现 HTTP Bad Request 错误

Question

我有一个具有以下配置的 WCF 服务:

<system.serviceModel>
    <behaviors>
        <serviceBehaviors>
            <behavior name="MetadataEnabled">
                <serviceDebug includeExceptionDetailInFaults="true" />
                <serviceMetadata httpGetEnabled="true" />
            </behavior>
        </serviceBehaviors>
     </behaviors>
      <services>
          <service behaviorConfiguration="MetadataEnabled" name="MyNamespace.MyService">
              <endpoint name="BasicHttp"
                        address=""
                        binding="basicHttpBinding"
                        contract="MyNamespace.IMyServiceContract" />
              <endpoint name="MetadataHttp"
                        address="contract"
                        binding="mexHttpBinding" 
                        contract="IMetadataExchange" />
              <host>
                  <baseAddresses>
                      <add baseAddress="http://localhost/myservice" />
                  </baseAddresses>
              </host>
          </service>
    </services>
</system.serviceModel>

在 WcfSvcHost.exe 进程中托管服务时，如果我浏览到 URL:

http://localhost/myservice/contract

在服务元数据可用的地方，我收到了 HTTP 400 Bad Request 错误。

通过检查 WCF 日志，我发现正在抛出一个 System.Xml.XmlException 异常并显示以下消息:“无法读取消息正文，因为它是空的。"
这是日志文件的摘录:

<Exception>
<ExceptionType>
System.ServiceModel.ProtocolException, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
</ExceptionType>
<Message>There is a problem with the XML that was received from the network. See inner exception for more details.</Message>
<StackTrace>
at System.ServiceModel.Channels.HttpRequestContext.CreateMessage()
at System.ServiceModel.Channels.HttpChannelListener.HttpContextReceived(HttpRequestContext context, ItemDequeuedCallback callback)
at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContextCore(IAsyncResult result)
at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContext(IAsyncResult result)
at System.ServiceModel.Diagnostics.Utility.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
at System.Net.ListenerAsyncResult.WaitCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)
</StackTrace>
<InnerException>
<ExceptionType>System.Xml.XmlException, System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType>
<Message>The body of the message cannot be read because it is empty.</Message>
<StackTrace>
at System.ServiceModel.Channels.HttpRequestContext.CreateMessage()
at System.ServiceModel.Channels.HttpChannelListener.HttpContextReceived(HttpRequestContext context, ItemDequeuedCallback callback)
at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContextCore(IAsyncResult result)
at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContext(IAsyncResult result)
at System.ServiceModel.Diagnostics.Utility.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at System.Net.LazyAsyncResult.Complete(IntPtr userToken)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(Object result, IntPtr userToken)
at System.Net.ListenerAsyncResult.WaitCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* nativeOverlapped)
at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pOVERLAP)
</StackTrace>
</InnerException>
</Exception>

如果我改为浏览 URL:

http://localhost/myservice?wsdl

一切正常，我得到了 WSDL 契约(Contract)。此时，我还可以完全删除 “MetadataHttp” 元数据端点，这不会有任何区别。

我使用的是 .NET 3.5 SP1。有没有人知道这里可能出了什么问题？

Answer 1

我想我找到问题所在了。

如果我浏览到 URL:

http://localhost/myservice/contract

使用 WcfTestClient 应用程序，我可以成功检索服务元数据。
所以错误实际上只发生在我通过网络浏览器请求 URL 时。

HTTP Bad Request 错误源于浏览器发出 HTTP GET 请求，其中消息的内容在 HTTP header 中，而正文为空。
这这正是 WCF mexHttpBinding 所提示的!

为了通过 Web 浏览器访问服务契约(Contract)，您必须在服务行为中明确启用它:

<serviceBehaviors>
    <behavior name="MetadataEnabled">
        <serviceMetadata httpGetEnabled="true" />
    </behavior>
</serviceBehaviors>

请求的 URL 变为:

http://localhost/myservice?wsdl

所以，事实证明我发布这个问题有点太快了。不过，我还是会保留它只是为了记录。