Wednesday, 26 November 2008

WCF and Custom Exceptions

From within the Server we throw custom exceptions which contain custom data that the client code can use. To transport these across WCF to the client we wrap them in a FaultException like this:
catch (BlockBookingInvalidFloorsException ex)
{
throw new FaultException(ex);
}
Despite the fact that both the custom exception and the contained classes are marked as [Serializable()] it results in a WCF CommunicationException.

To resolve this we now add this new constructor:
public BlockBookingInvalidFloorsException(SerializationInfo serializationInfo, StreamingContext streamingContext)
: base(serializationInfo, streamingContext) { }
Martin found this blog with a fuller explanation: WCF and Custom Exceptions

Claus suggests that custom exceptions should derive from either CommunicationException or System.Exception. Our's derive from ApplicationException with no problem, indeed the ApplicationException already includes this constructor (protected).

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