- Wout

One wierd thing that I have noticed was, though exceptions cannot be serialized using DataContractSerializer hance the NetDataContractSerializer. However is the client throws FaulException instead of the exception i.e. instead of client throwing say ArgumentNullException if it throws FaultException, the error handler will be bypassed and the exception get serialized using the normal DataContractSerializer without any serialization exception. And at the client end you would IClientMessageInspector would throw serialization exception.

ExceptionMarshallingMessageInspector.cs:

40: const string detailElementName = “detail”;

47: if (reader.NodeType == XmlNodeType.Element && reader.LocalName.ToLower() == detailElementName)

54: if (reader.NodeType != XmlNodeType.Element || reader.LocalName.ToLower() != detailElementName)

I have found one somewhat big problem with the implementation provided in that the stack trace doesn’t appear to be preserved from the server. I understand that this may actually be desirable depending on the amount of information that one desires to disclose to the client however I have found a hack that seems to be working for us in the meantime.

In the AfterReceiveReply() method of the ExceptionMarshallingMessageInspector class the following code can be changed as shown below.
______________________
object faultDetail = ReadFaultDetail(copy);
Exception exception = faultDetail as Exception;
if (exception != null)
{
throw exception;
}
______________________

By adding a little reflection magic to the code shown above as shown below, you should then see the server stack trace.

______________________
object faultDetail = ReadFaultDetail(copy);
Exception exception = faultDetail as Exception;
if(exception != null)
{
// NB: Error checking etc. excluded
// Get the _remoteStackTraceString of the Exception class
FieldInfo remoteStackTraceString = typeof(Exception).GetField(
“_remoteStackTraceString”,
BindingFlags.Instance | BindingFlags.NonPublic
);

// Set the InnerException._remoteStackTraceString to the current InnerException.StackTrace
remoteStackTraceString.SetValue(
exception,
exception.StackTrace + Environment.NewLine
);

throw exception;
}
______________________

I can’t take all the credit for this hack though since I found it at Chris Taylor’s blog.

http://www.dotnetjunkies.com/WebLog/chris.taylor/archive/2004/03/03/8353.aspx

NOTE: With this technique you the original stack trace however it is muddied up with some of the intermediate exception marshaling code which would be nice to bypass and it appears that the proxy automatically shoves some of the client side portions of the stack trace under the “Server stack trace” section.