Abstract classes in client lib, and concrete class in shared lib - wcf

Question

How do I solve the serialization problem with abstract class defined in a shared client library, and concrete implementation in a server side library.
Interface in shared client library :
[ServiceContract(SessionMode=SessionMode.Required)]
[ServiceKnownType(typeof(SharedClient.Shape))]
public interface IMyInterface
{
void UploadDrawing(Drawing dr);
}
Concreate Drawing class in shared client library :
[DataContract]
[KnownType(typeof(SharedClient.Shape))]
public class Drawing
{
public Shape s;
}
Abstract class in shared client library :
[DataContract]
abstract public class Shape
{
[DataMember]
public abstract string Name;
}
Concrete class implementation in separate library which references the client library :
[DataContract]
public class Cirle : ClientLibrary.Shape
{
public override string Name { get; set; }
}
I keep getting the exception message:
There was an error while trying to serialize parameter
http://tempuri.org/:Drawing. The InnerException message was 'Type
'Circle' with data contract name
'Circle:http://schemas.datacontract.org/2004/07/' is not expected.
Consider using a DataContractResolver or add any types not known
statically to the list of known types - for example, by using the
KnownTypeAttribute attribute or by adding them to the list of known
types passed to DataContractSerializer.'. Please see InnerException
for more details.

Answer 1

KnownType works in other way. If you want to use KnownType attribute you must use it on the base class to define its child:
[DataContract]
[KnownType(typeof(Circle))]
abstract public class Shape
{
[DataMember]
public abstract string Name;
}
That will not be too much helpful in your case. Try to put ServiceKnownType with concrete class on your interface:
[ServiceContract(SessionMode=SessionMode.Required)]
[ServiceKnownType(typeof(Circle))]
public interface IMyInterface
{
void UploadDrawing(Drawing dr);
}
You doesn't have to define Shape as ServiceKnownType - it is already known because it is used in Drawing but WCF yet doesn't know the Circle type.