Olaf Kummer

The Petri net markup language: concepts, technology, and tools

The Petri Net Markup Language (PNML) is an XML-based interchange format for Petri nets. In order to support different versions of Petri nets and, in particular, future versions of Petri nets, PNML allows the definition of Petri net types. Due to this flexibility, PNML is a starting point for a standard interchange format for Petri nets. This paper discusses the design principles, the basic concepts, and the underlying XML technology of PNML. The main purpose of this paper is to disseminate the ideas of PNML and to stimulate discussion on and contributions to a standard Petri net interchange format.

An Extensible Editor and Simulation Engine for Petri Nets: Renew

Renew is a computer tool that supports the development and execution of object-oriented Petri nets, which include net instances, synchronous channels, and seamless Java integration for easy modelling. Renew is available free of charge including the Java source code. Due to the growing application area more and more requirements had to be fulfilled by the tool set. Therefore, the architecture of the tool has been refactored to gain more flexibility. Now new features allow for plug-ins on the level of concepts (net formalisms) and on the level of applications (e.g. workflow or agents).

Petri's Axioms of Concurrency- A Selection of Recent Results

Concurrency theory, as developed by Carl Adam Petri, is an axiomatic theory of binary relations of concurrency (co) and causality (li). This work deals with interactions between axioms and studies properties of concurrency structures, the models of this theory. In contrast to other treatments concurrency theory will be investigated in its general form, which does not require an underlying partial order of causality. Some difficulties are illustrated by counterexamples and possible extensions of the original set of axioms are proposed and analyzed.

Content Schema Evolution in the CoreMedia®; Content Application Platform CAP

Based on experience gathered with several releases of the CoreMedia Content Application Platform (CAP), we argue that a modern, generalized Content Management System should, as database systems do, support explicit content schemata. To control the inevitable evolution of the content schema, the schema should be subject to configuration management together with the actual content. We propose a two-layered approach to content schema evolution consisting of - a system level responsible for bookkeeping and integrity issue detection, and - a semi-automatic application level responsible for resolving schema-related issues.A prototype using the proposed approach has been successfully implemented at CoreMedia.

Symmetric Communication between Coloured Petri Net Simulations and Java-Processes

In order to widen the applicability of Coloured Petri Nets for the specification and design of large scale distributed applications, a framework has been developed that supports the interaction of Design/ CPN and Java processes. The underlying architecture can be used for other tools. Thereby a seamless embedding of the two worlds of Petri nets and object-oriented programming is achieved, allowing problem oriented modelling at different abstraction levels in a fully distributed environment. The general possibilities to connect Coloured Petri Net simulations with remote processes are discussed and a specific implementation of the required framework is sketched. Promising application areas are named and for some of them concrete example models are provided.