错误“此消息不支持该操作，因为它已被读取”

Question

我遇到了以下线程中列出的相同问题。

WSDL第一个WCF服务器，其中客户端不发送SOAPAction

我执行了同一个线程中列出的步骤（也显示在下面）

1）下载Microsoft WCF示例。 从WF_WCF_Samples \\ WCF \\ Extensibility \\ Interop \\ RouteByBody \\ CS \\ service将以下文件添加到项目中

DispatchByBodyOperationSelector.cs

DispatchByBodyBehaviorAttribute.cs

2）将以下属性添加到您的界面（ServiceContract旁边）

XmlSerializerFormat

DispatchByBodyBehavior

3）将以下内容添加到服务界面

[OperationContract(Action = "")]

public void DoNothing()
{
}

4）对于我的服务，WrapperName和Wrappernamespace对于所有消息都为空。 我不得不进入DispatchByBodyBehaviorAttribute并编辑ApplyDispatchBehavior（）以添加以下行来检查：

 if (qname.IsEmpty) {
     qname = new XmlQualifiedName(operationDescription.Messages[0].Body.Parts[0].Name, operationDescription.Messages[0].Body.Parts[0].Namespace);
 }

现在，我收到一条错误消息“此消息无法支持该操作，因为它已被读取”。 我打开了跟踪并捕获了堆栈跟踪（下图）。 如果有人知道如何解决这个问题，我很感激您是否可以发表一些评论。 谢谢你的帮助！

at System.ServiceModel.Channels.Message.GetReaderAtBodyContents()
at System.ServiceModel.Dispatcher.OperationFormatter.DeserializeBodyContents(Message message, Object[] parameters, Boolean isRequest)
at System.ServiceModel.Dispatcher.OperationFormatter.DeserializeRequest(Message message, Object[] parameters)
at System.ServiceModel.Dispatcher.DispatchOperationRuntime.DeserializeInputs(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage41(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage2(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1(MessageRpc& rpc)
at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)
at System.ServiceModel.Dispatcher.ChannelHandler.DispatchAndReleasePump(RequestContext request, Boolean cleanThread, OperationContext currentOperationContext)
at System.ServiceModel.Dispatcher.ChannelHandler.HandleRequest(RequestContext request, OperationContext currentOperationContext)
at System.ServiceModel.Dispatcher.ChannelHandler.AsyncMessagePump(IAsyncResult result)
at System.ServiceModel.Dispatcher.ChannelHandler.OnAsyncReceiveComplete(IAsyncResult result)
at System.Runtime.Fx.AsyncThunk.UnhandledExceptionFrame(IAsyncResult result)
at System.Runtime.AsyncResult.Complete(Boolean completedSynchronously)
at System.Runtime.InputQueue`1.AsyncQueueReader.Set(Item item)
at System.Runtime.InputQueue`1.EnqueueAndDispatch(Item item, Boolean canDispatchOnThisThread)
at System.Runtime.InputQueue`1.EnqueueAndDispatch(T item, Action dequeuedCallback, Boolean canDispatchOnThisThread)
at System.ServiceModel.Channels.SingletonChannelAcceptor`3.Enqueue(QueueItemType item, Action dequeuedCallback, Boolean canDispatchOnThisThread)
at System.ServiceModel.Channels.HttpChannelListener.HttpContextReceived(HttpRequestContext context, Action callback)
at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContextCore(IAsyncResult result)
at System.ServiceModel.Channels.SharedHttpTransportManager.OnGetContext(IAsyncResult result)
at System.Runtime.Fx.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>


class DispatchByBodyElementOperationSelector : IDispatchOperationSelector
{
    Dictionary<XmlQualifiedName, string> dispatchDictionary;

    public DispatchByBodyElementOperationSelector(Dictionary<XmlQualifiedName, string> dispatchDictionary)
    {
        this.dispatchDictionary = dispatchDictionary;            
    }

    #region IDispatchOperationSelector Members

    private Message CreateMessageCopy(Message message, XmlDictionaryReader body)
    {
        //Message copy = Message.CreateMessage(message.Version, message.Headers.Action, body);
        //copy.Headers.CopyHeaderFrom(message, 0);
        //copy.Properties.CopyProperties(message.Properties);
        //return copy;    

        MessageBuffer buffer = message.CreateBufferedCopy(Int32.MaxValue);
        Message copy = buffer.CreateMessage();
        buffer.Close();
        copy.Headers.CopyHeaderFrom(message, 0);
        copy.Properties.CopyProperties(message.Properties);

        return copy;
    }

    public string SelectOperation(ref System.ServiceModel.Channels.Message message)
    {
        XmlDictionaryReader bodyReader = message.GetReaderAtBodyContents();

        XmlQualifiedName lookupQName = new XmlQualifiedName(bodyReader.LocalName, bodyReader.NamespaceURI);
        message = CreateMessageCopy(message,bodyReader);
        if (dispatchDictionary.ContainsKey(lookupQName))
        {
            return dispatchDictionary[lookupQName];
        }
        else
        {
            return null;
        }
    }

    #endregion
}

[AttributeUsage(AttributeTargets.Class|AttributeTargets.Interface)]
sealed class DispatchByBodyBehaviorAttribute : Attribute, IContractBehavior
{
    #region IContractBehavior Members

    public void AddBindingParameters(ContractDescription contractDescription, ServiceEndpoint endpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
    {
        // no binding parameters need to be set here
        return;
    }

    public void ApplyClientBehavior(ContractDescription contractDescription, ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.ClientRuntime clientRuntime)
    {
        // this is a dispatch-side behavior which doesn't require
        // any action on the client
        return;
    }

    public void ApplyDispatchBehavior(ContractDescription contractDescription, ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.DispatchRuntime dispatchRuntime)
    {
        // We iterate over the operation descriptions in the contract and
        // record the QName of the request body child element and corresponding operation name
        // to the dictionary to be used for dispatch 
        Dictionary<XmlQualifiedName,string> dispatchDictionary = new Dictionary<XmlQualifiedName,string>();
        foreach( OperationDescription operationDescription in contractDescription.Operations )
        {
            XmlQualifiedName qname =
                new XmlQualifiedName(operationDescription.Messages[0].Body.WrapperName, operationDescription.Messages[0].Body.WrapperNamespace);




            if (qname.IsEmpty)
            {
                qname = new XmlQualifiedName(operationDescription.Messages[0].Body.Parts[0].Name, operationDescription.Messages[0].Body.Parts[0].Namespace);
            }

            dispatchDictionary.Add(qname, operationDescription.Name);                
        }

        // Lastly, we create and assign and instance of our operation selector that
        // gets the dispatch dictionary we've just created.
        dispatchRuntime.OperationSelector = 
            new DispatchByBodyElementOperationSelector(dispatchDictionary);
    }

    public void Validate(ContractDescription contractDescription, ServiceEndpoint endpoint)
    {
        // 
    }

    #endregion
}

Answer 1

您应该使用MessageBuffer.CreateMessage ：

Message实例的主体只能被使用或写入一次。 如果您希望多次使用Message实例，则应使用MessageBuffer类将整个Message实例完全存储到内存中。

http://msdn.microsoft.com/en-us/library/system.servicemodel.channels.messagebuffer.aspx

我当前项目的代码：

public void AfterReceiveReply(ref System.ServiceModel.Channels.Message reply, object correlationState)
{
    MessageBuffer buffer = reply.CreateBufferedCopy(Int32.MaxValue);
    reply = buffer.CreateMessage();
    Message m = buffer.CreateMessage();
    LogMessage(m, " Response => ");
}

为Message param添加ref并返回新消息。

 private Message CreateMessageCopy(ref Message message, XmlDictionaryReader body)
{
...
   message = buffer.CreateMessage();

Answer 2

我有一个非常类似的问题，使用WCF Samples中的代码（精确地说是RouteByBody），并且能够以不同的方式解决它，所以我会在这里发布它，以防它对任何人有帮助。

情况：客户端应用程序（使用者）将在Release中工作，但是，当附加调试器时，它将始终失败，并显示错误“此消息因为已被读取而无法支持该操作” 。

经过大量跟踪和记录WCF消息之后，唯一对我有用的解决方案就是如此简单：

我的服务托管在IIS上，并在web.config的<compilation>部分中使用debug="true" 。

在服务上将它更改为debug="false"修复了我的所有问题。

Answer 3

如果你正在调试服务，Dmitry Harnitski的答案不起作用（它会给你一个“这条消息不能支持操作，因为它已被复制。”错误。）

即使在调试模式下也可以：

XmlDictionaryReader GetReader(ref Message message)
{
    MessageBuffer buffer = message.CreateBufferedCopy(Int32.MaxValue);
    message = buffer.CreateMessage();
    newMessage = buffer.CreateMessage();
    XmlDictionaryReader rv = buffer.CreateMessage().GetReaderAtBodyContents();
    buffer.Close();
    return rv;
}

static System.ServiceModel.Channels.Message newMessage = null;
static System.ServiceModel.Channels.Message lastMessage = null;

public string SelectOperation(ref System.ServiceModel.Channels.Message message)
{
    try
    {
        if(message == lastMessage)
            message = newMessage;

        XmlDictionaryReader bodyReader = GetReader(ref message);

        lastMessage = message;

        XmlQualifiedName lookupQName = new XmlQualifiedName(bodyReader.LocalName, bodyReader.NamespaceURI);
        if (dispatchDictionary.ContainsKey(lookupQName))
        {
            return dispatchDictionary[lookupQName];
        }
        else
        {
            return null;
        }
    }
    catch(Exception ex)
    {
        throw ex;
    }
}