A formal specification framework for object-oriented distributed systems

In this paper, we present the Concurrent Object-Oriented Petri Nets (CO-OPN/2) formalism devised to support the specification of large distributed systems. Our approach is based on two underlying formalisms: order-sorted algebra and algebraic Petri nets. With respect to the lack of structuring capabilities of Petri nets, CO-OPN/2 has adopted the object-oriented paradigm. In this hybrid approach (model- and property-oriented), classes of objects are described by means of algebraic Petri nets, while data structures are expressed by order-sorted algebraic specifications. An original feature is the sophisticated synchronization mechanism. This mechanism allows to involve many partners in a synchronization and to describe the synchronization policy. A typical example of distributed systems, namely the Transit Node, is used throughout this paper to introduce our formalism and the concrete specification language associated with it. By successive refinements of the components of the example, we present, informally, most of the notions of CO-OPN/2. We also give some insights about the coordination layer, Context and Objects Interface Language (COIL), which is built on top of CO-OPN/2. This coordination layer is used for the description of the concrete distributed architecture of the system. Together, CO-OPN/2 and COIL provide a complete formal framework for the specification of distributed systems