Why WCF client not receiving SOAP Fault as FaultException? - wcf

Question

I am using a WCF client to consume a non-WCF SOAP 1.2 web service. When receiving a SOAP fault as shown below, I receive a ProtocolException instead of a FaultException. There are no problems with the communication binding and the request is being processed successfully. But I cannot access the fault error in my WCF client. Any ideas?
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope" xmlns:SOAP-ENC="http://www.w3.org/2003/05/soap-encoding" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:c14n="http://www.w3.org/2001/10/xml-exc-c14n#" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsa5="http://www.w3.org/2005/08/addressing" xmlns:wsr="http://docs.oasis-open.org/wsrf/r-2" xmlns:xmime5="http://www.w3.org/2005/05/xmlmime" xmlns:xop="http://www.w3.org/2004/08/xop/include" xmlns:tt="http://www.onvif.org/ver10/schema" xmlns:wsbf="http://docs.oasis-open.org/wsrf/bf-2" xmlns:wstop="http://docs.oasis-open.org/wsn/t-1" xmlns:ns10="http://www.onvif.org/ver10/events/wsdl/PausableSubscriptionManagerBinding" xmlns:ns3="http://www.onvif.org/ver10/events/wsdl/PullPointSubscriptionBinding" xmlns:ns4="http://www.onvif.org/ver10/events/wsdl/EventBinding" xmlns:tev="http://www.onvif.org/ver10/events/wsdl" xmlns:ns5="http://www.onvif.org/ver10/events/wsdl/SubscriptionManagerBinding" xmlns:ns6="http://www.onvif.org/ver10/events/wsdl/NotificationProducerBinding" xmlns:ns7="http://www.onvif.org/ver10/events/wsdl/NotificationConsumerBinding" xmlns:ns8="http://www.onvif.org/ver10/events/wsdl/PullPointBinding" xmlns:ns9="http://www.onvif.org/ver10/events/wsdl/CreatePullPointBinding" xmlns:wsnt="http://docs.oasis-open.org/wsn/b-2" xmlns:tds="http://www.onvif.org/ver10/device/wsdl" xmlns:ter="http://www.onvif.org/ver10/error" xmlns:timg="http://www.onvif.org/ver20/imaging/wsdl" xmlns:tptz="http://www.onvif.org/ver20/ptz/wsdl" xmlns:trt="http://www.onvif.org/ver10/media/wsdl">
<SOAP-ENV:Header/>
<SOAP-ENV:Body>
<SOAP-ENV:Fault>
<SOAP-ENV:Code>
<SOAP-ENV:Value>SOAP-ENV:Sender</SOAP-ENV:Value>
<SOAP-ENV:Subcode>
<SOAP-ENV:Value>ter:InvalidArgVal</SOAP-ENV:Value>
<SOAP-ENV:Subcode>
<SOAP-ENV:Value>ter:NoSource</SOAP-ENV:Value>
</SOAP-ENV:Subcode>
</SOAP-ENV:Subcode>
</SOAP-ENV:Code>
<SOAP-ENV:Reason>
<SOAP-ENV:Text xml:lang="en">Not exist</SOAP-ENV:Text>
</SOAP-ENV:Reason>
<SOAP-ENV:Detail>
<SOAP-ENV:Text xml:lang="en">The requested VideoSource does not exist.</SOAP-ENV:Text>
</SOAP-ENV:Detail>
</SOAP-ENV:Fault>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
System.ServiceModel.ProtocolException
"The remote server returned an unexpected response: (400) Bad Request.
StackTrace
"Server stack trace:
at System.ServiceModel.Channels.HttpChannelUtilities.ValidateRequestReplyResponse(HttpWebRequest request, HttpWebResponse response, HttpChannelFactory factory, WebException responseException, ChannelBinding channelBinding)
at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs)
at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
Exception rethrown at [0]:
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
at OnvifProxy.ImagingPort.SetImagingSettings(String VideoSourceToken, ImagingSettings20 ImagingSettings, Boolean ForcePersistence)
at OnvifProxy.ImagingPortClient.SetImagingSettings(String VideoSourceToken, ImagingSettings20 ImagingSettings, Boolean ForcePersistence) in D:\..\Proxies\OvifServices.cs:line 19005
at Integral.Common.IPCameras.ONVIF.Services.ImagingService.SetImageSettings(String pVideoSourceToken, ImagingSettings20 pImageSettings) in D:\..\Services\ImagingService.cs:line 375" string

Answer 1

I would recommend using Fiddler to intercept the raw response. In these situations (interop), it's best to bypass WCF entirely and read the response message as it arrives "on the wire." Trying to debug a non-WCF fault or a deserialization error through WCF can only give you headaches. =)
Most often, looking at the raw response will point the problem out like a sore thumb.

Answer 2

I think the problem you're having is because the server returns a 400 HTTP response code. Apparently the bodies of messages with a response code other than 200 are not accessible to the Silverlight client.
If you had control of the server, you could modify it to send a 200 response code instead of 400, but if you don't have control of the server, you need to modify your client to accept response codes other than 200.
I found some instructions here to change the client to use an alternative HTTP stack. I had the same problem as you (but with HTTP response code 500) and this fixed the problem. All you have to do is add this code at the beginning of your Silverlight application (for example, on the constructor for the MainPage class):
bool registerResult = WebRequest.RegisterPrefix("http://", WebRequestCreator.ClientHttp);

Answer 3

Is the method being called marked with the IsOneWay=true attribute in the generated proxy class?
If it is then there is no back channel for the SOAP fault to be received on but WCF can get it back some other way and this shows up as the ProtocolException. As far as I am aware you need to have IsOneWay=false to get a SOAP fault.