Evolving Services from a Contractual Perspective

In an environment of constant change, driven by competition and innovation, a service can rarely remain stable especially when it depends on other services to fulfill its functionality. However, uncontrolled changes can easily break the existing relationships between a service and its environment (its customers and providers). In this paper we present an approach that allows for the controlled evolution of a service by leveraging the loosely-coupled nature of the SOA paradigm. More specifically, we formalize the notion of contracts between interacting services that enable their independent evolution and we investigate under which criteria can changes to a contract-bound service, or even to the contract itself, be transparent to the environment of the service.