Synchronous Interactions of Objects in Object Oriented Petri Nets

This paper presents an additional concept of object interactions in Object oriented Petri nets. Object oriented Petri nets (OOPN) is a formalism developed at the Department of Computer Science and Engineering FEI VUT in Brno during last few years in order to overcome problems with modeling highly dynamic systems by means of Petri nets. An experimental language based on OOPN is called PNtalk. OOPN and PNtalk are comparable with other well known approaches to object orientation in Petri nets. It is based on active objects communicating by a client-server (request-reply) protocol. Objects are described by high-level Petri nets enriched with a message sending mechanism and by a possibility to dynamically instantiate objects and methods. In order to improve its applicability in modeling some non-trivial real-world systems such as flexible manufacturing and workflow systems on an appropriate level of abstraction a new feature was added to OOPN. It allows synchronous interactions of objects and does not violate the pure object orientation of OOPN. This new concept is represented by synchronous ports. Its basic principle as well as some methodological aspects are discussed in this paper.