使用Service Bus 1.0的继承类的DataContract和KnownTypes

Question

Hi I have the following class hierarchy:

public class SuperJob{
}

public class JobA:SuperJob{
}

public class JobB:SuperJob{
}

When i try to deserialise a SuperJob i get

Expecting element 'SuperJob' from namespace 'http://schemas.datacontract.org/2004/07/...'.. Encountered 'Element'  with name 'JobA', namespace 'http://schemas.datacontract.org/2004/07/...'.

I have annotated my classes as follows:

[DataContract]
[KnownType(typeof(JobA))]
[KnownType(typeof(JobB))]
public class SuperJob{
}

[DataContract]
public class JobA:SuperJob{
}

[DataContract]
public class JobB:SuperJob{
}

Not sure what i am doing wrong? Any ideas how do i fix this?

Answer 1

Use [ServiceKnownType] attribute on your service :

[ServiceKnownType(typeof(JobA))]
[ServiceKnownType(typeof(JobB))]
public interface IJobService 
{
.... methods
}

Another approach would be to pass knowntypes in DataContractSerializer constructor.

List<Type> knownTypeList = new List<Type>();
knownTypeList.Add(typeof(JobA));
knownTypeList.Add(typeof(JobB));

// Create a DatatContractSerializer with the collection.
DataContractSerializer ser2 = new DataContractSerializer(
                                  typeof(SuperJob), knownTypeList);

Answer 2

Managed to fix this issue, there is a bug in the way the service bus instantiates the serialiser. looks like internally it instantiates the serialiser with JobA.getType(). So the best way forward is to create your own DataSerializer object which uses typeOf(JobA) and pass that in both when sending the message on to the bus and reading off the bus.