silverlight client doesnt understand faultexception - silverlight

Question

I have a WCF service that throws an exception which I am trying to catch unsucessfully in my silverlight client code. I am using Undeclared Faults for Debugging purposes and this is my service method :
[OperationContract]
public ServiceResponse MyWCFServiceMethod()
{
ServiceResponse resp = new ServiceResponse ();
//code for setting resp...
//purposely throw error here.
throw new FaultException(new FaultReason(new FaultReasonText("My fault Reason!")),new FaultCode("my fault code here"));
return resp;
}
Now in my silverlight client view model, in the service's callback method, I try to handle it like this:
private void MyServiceCallback(MyWCFServiceMethodCompletedEventArgs e)
{
if (e.Error == null)
{
//proceed normally
}
else if (e.Error is FaultException)
{
FaultException<ExceptionDetail> fault = e.Error as FaultException<ExceptionDetail>;
MessageBox.Show(fault.Detail.Message);
MessageBox.Show(fault.Reason.ToString());
}
}
at this line else if (e.Error is FaultException) I still get System.Net.WebException {The remote server returned an error: NotFound.}
These are the config entries
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="true" />
This is the service class declaration
[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class MySilverlightWCFService
{
....
This service is in another project within the same silverlight solution.
Why is my silverlight client not able to get the fault exception I am throwing?
Thanks for your time...

Answer 1

ok so finally what seems to be the way to make this work is to get one line of code added to the service just before you throw the fault exception!
System.ServiceModel.Web.WebOperationContext.Current.OutgoingResponse.StatusCode = System.Net.HttpStatusCode.OK;
Then throw the actual exception:
throw new FaultException(new FaultReason(new FaultReasonText("My fault Reason!")),new FaultCode("my fault code here"));
Then in silverlight modify the service call back error handling section from what I put in my question above to:
//else if (e.Error is FaultException)
else
{
//FaultException<ExceptionDetail> fault = e.Error as FaultException<ExceptionDetail>;
//MessageBox.Show(fault.Detail.Message);
FaultException fault = e.Error as FaultException;
MessageBox.Show(fault.Reason.ToString());
}
That worked for me. Ugly way!
I will try with Declared faults when I get the time.

Answer 2

Check out the SilverlightFaultBehavior. It will handle changing the status code for you.

Answer 3

The server is probably throwing a HTTP 500 response code that Silverlight is ignoring. You must change the service to return a HTTP code that Silverlight will accept.
From Data Performance and Fault Strategies in Silverlight 3: (This article will show you how to return WCF faults to Silverlight.)
Infamous NotFound Error:
When the exception is raised, an HTTP
status
code of 500 is returned to
Silverlight. The browser networking
stack prevents Silverlight from
reading responses with a status code
of 500, so any SOAP fault information
contained within is unavailable to the
Silverlight client application. Even
if the message could be retrieved,
Silverlight 2 is not capable of
converting the fault back into a
managed exception. Both of these
issues have been addressed in
Silverlight 3.