Vladimir Janousek

PNtalk - a Computerized Tool for Object Oriented Petri Nets Modelling

The paper deals with a new formalism and a tool for concurrent systems modelling and prototyping. This formalism, Object Oriented Petri Net (OOPN), combines the descriptive power of Petri nets with the well known advantages of object oriented modelling techniques. In the paper there are presented the structure of system specifications by means of OOPNs, principles of their dynamic behaviour as well as some basic features of a computerized tool which supports practical use of OOPNs. This tool works with a language called PNtalk which is based on the OOPNs and the language Smalltalk.

System Design with Object Oriented Petri Nets Formalism

The actual trend in the research of system design aims at an efficiency and safety of developing processes as well as at the quality of resulted systems. There were investigated and developed many methodologies of system design based on models-they are known as model-based design. These methodologies use executable semi-formal models allowing for transformations including code generation in selected language. Nevertheless, the further development or debugging by means of prime models is impossible. This paper brings an outline of our approach to model-based design based on the object oriented Petri nets formalism allowing for clear modeling, the possibility to check correctness by simulation techniques as well as by formal verifications. The model is an executable program valid through all development stages including the target application. The paper depicts the basis of the formalism and used techniques.

OOPN and DEVS Formalisms for System Specification and Analysis

The paper describes an approach to Simulation Based Design (SBD) of systems, which combines design models with simulation models. Obviously, a system representation allowing simulation analysis differs from design models and have to be generated or the design formalism has to be extended by special formalism. The presented approach uses formalisms which can be used for system design as well as system analysis. It uses high-level Petri nets, objects and systems-theoretic approach represented by DEVS formalism. The paper outlines the design methodology of SBD based on the formalism and demonstrates a technique of simulation analysis on the simplified example.

Operating System for Petri Nets-Specified Reconfigurable Embedded Systems

This paper describes an operating system (OS) and supporting development tools for Petri nets-specified dynamically reconfigurable embedded control systems construction. We use nets-within-nets paradigm formalized by Reference Nets. This formalism allows for layered architecture that enables the dynamic reconfigurability of the modeled system. Our specific contribution is the idea of code generation for a virtual machine (VM), which is able to interpret a model composed of a set of Petri nets. This VM is part of the OS for the target microcontroller. The proposed OS and application architecture then enables incremental changes within the system specification and implementation during its life-time.

PNagent: A Framework for Modelling BDI Agents Using Object Oriented Petri Nets

Petri nets have proven to be a valuable tool for modelling concurrent systems. As such, they should be suitable for modelling agent and multi-agent systems, as these are inherently concurrent. Nevertheless, there are not many systems that allow modelling of the whole multi-agent system in Petri nets. The use of Petri nets is usually limited to sub-problems, such as verification of interaction protocols. This paper describes the main concepts of PNagent - a tool for modelling BDI agents using the formalism of object oriented Petri nets (OOPN). PNagent allows development, testing and running software agents in a consistent graphical environment. The framework is suitable for prototyping and experiments with both multi-agent applications and the particular agent architecture itself. At the same time, thanks to the formal nature of its underlying paradigm, it provides means for verification of agentpsilas properties.

Object Oriented Petri Nets Modelling Techniques Case Study

The importance of models used in the area of system design is growing. There were investigated and developed many methodologies of system design based on models - they are known as model-based design. These methodologies use semi-formal models and need for model transformations to check correctness or to get a final application. Formal models, by contrast, allow for clear modelling and checking correctness by simulation techniques as well as by formal verifications. The model is an executable program valid through all development stages including the target application. There are several suitable formalisms, one of them is a formalism of Petri nets, especially its object variant, object oriented Petri nets (OOPN). The paper deals with application of OOPN formalism in the area of system design and demonstrates modeling techniques of OOPN on the case study of conference system design.

Towards Simulation-Based Design of the Software Systems

The current trend in research of methodology of systems design highlights the quality of resulted systems, however the research mainly aims at efficiency and safety of the development process itself. The most used development methodology used models as a basic means for description of systems. Although they can allow for model transformation, the designer has to adapt the resulted code manually. It can results in inconsistency among design models and their realization and the further development or debugging by means of prime models is impossible. The paper presents an approach to the system development, which is based on the concept of simulation based design allowing to see the system as a set of models in every development stage including its deployment.

Simulation Based Design of Control Systems Using DEVS and Petri Nets

Current model-based design methodologies use executable semi-formal models allowing for transformations including code generation. Nevertheless, the code should be finalized manually and further development or debugging by means of prime models is impossible. The paper introduces an approach to the system design called Simulation Based Design which uses fromalisms of DEVS (Discrete-Event Systems Specification) and Object Oriented Petri Nets (OOPN) allowing for clear modeling, a possibility to check correctness by means of simulation as well as by formal verification. The approach is based on techniques such as incremental development in the simulation, reality-in-the-loop simulation, and model-continuity. The model is understood as an executable program valid through all development stages including the deployment (the target system).

Modeling Deliberative Agents Using Object Oriented Petri Nets

Multi-agent systems are one of the prospect approaches to simplification of complex system development. They introduce a natural abstraction layer on top of autonomous actors. Since multi-agent systems are strongly parallel the appropriate paradigms or tools have to be used. This article will demonstrate the application of our developed kind of high-level Petri nets to the deliberative agent modeling and simulation. This formalism is called Object Oriented Petri Nets (OOPN). It introduces a powerful means for description of concurrency and a high level of system dynamism. Moreover, OOPNs are a part of a framework intended for simulation based design featuring model continuity. It means that a model developed incrementally in a simulated environment can become a part of target applications.

Modelling, prototyping, and verifying concurrent and distributed applications using object‐oriented Petri nets

This paper presents several research issues associated with the PNtalk language that is based on a certain kind of object‐oriented Petri nets (OOPNs) and intended mainly for modelling, prototyping, and verifying concurrent and distributed applications. The paper reviews the main concepts of PNtalk and OOPNs followed by a proposal of a system allowing prototypes based on PNtalk to be run in a distributed way. Furthermore, the first step made towards state spaces‐based formal analysis and verification over PNtalk OOPNs are also briefly mentioned in the paper.