WCF DataContractResolver

Question

I'm trying to follow a guide from http://kellabyte.com/2010/11/13/building-extensible-wcf-service-interfaces-with-datacontractresolver/ to create and attach a DataContractSerializer.

I've declared the serializer and implemented the methods, then attached it to both the client and server with the following code:

public class ModuleDataContractResolver : DataContractResolver {
    public override bool TryResolveType(Type type, Type declaredType,
                                            DataContractResolver knownTypeResolver,
                                            out System.Xml.XmlDictionaryString typeName,
                                            out System.Xml.XmlDictionaryString typeNamespace) {
       ....// I return a true/false here
    }

    public override Type ResolveName(string typeName, string typeNamespace,
                                         Type declaredType, DataContractResolver knownTypeResolver) {
       ....// I return a type here
    }

-

        var endpoint = _svcHost.Description.Endpoints.FirstOrDefault()
        ContractDescription cd = endpoint.Contract;
        foreach (OperationDescription opdesc in cd.Operations) {
            DataContractSerializerOperationBehavior serializerBehavior = opdesc.Behaviors.Find<DataContractSerializerOperationBehavior>();

            if (serializerBehavior == null) {
                serializerBehavior = new DataContractSerializerOperationBehavior(opdesc);
                opdesc.Behaviors.Add(serializerBehavior);
            }

            serializerBehavior.DataContractResolver = new ModuleDataContractResolver();
        }

Despite attaching the resolver, these two methods are called on neither the service nor the client, so the service is throwing an exception. Am I missing a step?

UPDATE: I'm not entirely convinced this isn't due to using MEF to return these types. The type in question is a MEF type, which is detected by the service but only exposed as an interface to the client, so the assembly is not loaded.

The idea is to have the service load a list of MEF modules, then expose them over this WCF service to the client as an interface.

Answer 1

Eventually finding the last solution anywhere which I hadn't tried, a post by dpblogs showed how to use an attribute in the service interface's method declarations. This finally caused my resolving methods to be called.