The Internationa[ Workshop on Discrete-Event System Design, DESDes'04, Septemcbcr [5-17,"2004; Dych6w near Zie[ona Gara, Poland A DESIGN AND VERIFICATION TOOL FOR THE PARALLEL SYSTEMS BY AN EXTENDED PETRI NET AND JAVA EXECUTOR Shin'nosuke Yamaguchi· Katsumi Wasaki·· Yasunari Shidama·· • J(yushu Institute of Technology, 680-4 J(awazu Iizuka-city Fukuoka 820-8502, Japan •• Shinshu University, 4-17-1 Wakasato Nagano-city Nagano 380-8553, Japan yamas@iizuka.isc.kyutech.ac.jp {wasaki,shidama }@cs.shinshu-u. ac . jp Abstract: In this paper, we propose a new method for parallel system design based on an expanded Logical Coloured Petri Net (LCPN). An LCPN is an extended Petri net that solves the problem of system description in the previously proposed place/transition nets and coloured Petri nets. This extension of Petri nets is suitable for designing complex control systems and for discussing methods of realistically evaluating such systems. In order to study the behaviour of the server system modelled with this net we simulated a Java program. This program confirmed that this extended Petri net is an effective tool for modelling parallel systems. Keywords: Petri net, Parallel system, XML, Concurrent Modelling, System Verification 1. INTRODUCTION In the design of system software, as a system becomes more complex, there are many costs associated with the platforms because any of the following problems may occur: (1) Various programming errors, or bugs, may simply be introduced (2) Verification of compliance with spec ifi cat ions is difficult trol flows. The mathematical nature of the Petri net can be used to obtain behavioural information of systems that operate in a dynamic environ- ment, especially if the time, or safety factors, make actual simulations of a system impracticable. A study of the relationships between the mathemat- ical objects of a Petri net can resolve conditions such as deadlocks, traps, reachability of marldng states, etc. that aid in the verification of system operations. (3) Tracing control flow/software is difficult for anyone other than the original programmers Using descriptive models of sequence control by Petri nets has become attractive due to its sim- plicity (T.Murata, 1989). A Petri net is a graphi- cal model that facilitates understanding the con- In the design of parallel systems, many modelling techniques adopting the concept of Petri net have been announced. A Petri net is suitable for de- scribing the characteristics of a parallel system and once a Petri net model has been created, it can be easily analysed. When designing time 61