Behavioural Types in CoOperative Objects

Behavioural typing and subtyping has proved to be a very useful concept for the support of incremental reuse in the area of object-oriented (O-O) languages. With the emergence of formalisms integrating the O-O approach and Petri nets, the question arises how behavioural subtyping may be supported by such formalisms. We present a formal framework for the definition of behavioural typing in CoOperative Objects, a concurrent Object Oriented language, based upon Client/Server Petri nets. This framework is based upon the preorder and equivalence relations which are considered in the study of concurrent systems, allowing to define various subtyping relations.