During the last few years there has been significant interest in combining the benefits of an object-oriented approach with Petri net formalism which is suitable to modelling and simulation of concurrent systems. Nevertheless, for modelling some system behaviour dynamic creation of new components is often needed. In this paper we introduce a formalism based on algebraic Petri nets using the object-orientation paradigm. Object classes are specified by means of algebraic Petri nets, synchronization expressions link the class instances and static as well as dynamic creation of objects is allowed. Inheritance and subtyping are considered as two different mechanisms. Inheritance is viewed as a duplication mechanism while subtyping is considered at a semantic level as a relation between models. The order-sorted algebras framework captures the subtyping notion between the objects which are identified by order-sorted values. Language semantics is defined through distributed transition systems over the models of algebraic specification.
