Services and Contracts: Coalgebraically 1

The popularity of service-oriented computing has not been accompanied by the necessary formalization of the notions being involved. This paper focuses on the development of a coalgebraic framework to support service-oriented application design. In this paper, the concepts are separated into three hierarchies – interfaces, contracts and services. Interfaces are specified by functors, and services are shown to be coalgebras of such functors, which should satisfy the axioms given in corresponding contracts. Different interfaces, contracts and services are related respectively by the morphisms between them. And the notion of bisimulation for services is derived from service morphisms, which captures the observational equivalence of services.