Will changing an Object signature break a WCF method call using that Object?

Question

If I have an object that holds the parameters for my method. I need to change the Object to have an additional property. I have full control over the server, but not over all of the clients. Will this change make those clients break?

I am using a self-hosted service with a binary endpoint.

I am new to WCF so my apologies if this is a silly question.

Answer 1

I guess you are asking about a class that represents your DataContract.

Learn about DataContract versioning and how various changes in your DataContract affect the compatibility in MSDN

Answer 2

In short the answer is No, it will not break the client code. The serialized graph of the data contract will deserialize to the available data members matching by their names and assigned through the property setter method. Obviously in this case, your newly added data member will not have value. Since you have full control on the server side code, you just have to make sure this newly added member need to be dealt in such a way that it is meaningful in the new implementation and allow for default/unassigned value.