WCF: Enforce equal DataContracts on both sides

Question

Hi all,

I'm wondering if it is possible to have WCF make sure that the DataContracts on both sides of a connection are exactly the same (and throw an exception when trying to connect if they are not).

For example, imagine this service:

[DataContract]
enum State
{
    [EnumMember]
    Red,
    [EnumMember]
    Yellow,
    [EnumMember]
    Green
}

[ServiceContract]
interface MyService
{
    [OperationContract]
    void SetState(State newState);
}

Now imagine the service is updated and now supports a new State, "Orange". The client still has the DataContract as shown above.

Now I want every call from the client to the service to fail because client and service are not using the same DataContract. Is this possible?

Thanks in advance for any help!

Answer 1

Well, you can't really do all that much about - but you could version your data contract with XML namespaces - something like this:

[DataContract(Namespace="http://data.yourcompany.com/DataSchema/2009/11")]
enum State
{
    [EnumMember]
    Red,
    [EnumMember]
    Yellow,
    [EnumMember]
    Green
}

Your client will now use this data contract - with the XML namespace.

If you change your data contract on the server next month, you could change the XML namespace to:

[DataContract(Namespace="http://data.yourcompany.com/DataSchema/2009/12")]
enum State
{
 ....
}

If you retire all service endpoints that used the "/2009/11" data contract and only have new endpoints with the new data contract, the clients won't be able to successfully call your service methods anymore (since the XML namespaces of the two DataContracts don't match).

Maybe that would be a way to go?

Marc