1. A method for exchanging information between information technology (IT) services, the method comprising: separating models for the IT services into an operation model and a structural model, the operation model and the structural model being linked by a service model, the service model being configurable to extend the operation model; configuring the operation model, the configuring of the operation model includes defining messages exchanged between the IT services; and configuring the structural model, the configuring of the structural model includes capturing a structure of the IT services, the service model includes an association with the structural model, the association of the service model with the structural model enabling substitution in a class, the substitution making the structural model opaque to the operation model.