The Petri Net Markup Language and ISO/IEC 15909-2: Concepts, Status, and Future Directions
Ekkart Kindler · 2006
The Petri Net Markup Language (PNML) is an XML-based interchange format for Petri nets. In order to support different versions of Petri nets, its focus is on universality and flexibility, which is achieved by a technique for defining new Petri net types. For presenting and precisely defining the XML-syntax, PNML uses UML meta models: The PNML Core Model defines the concepts shared by all kinds of Petri nets; additional Petri net type definitions are UML meta models for defining the concepts that are specific to particular kinds of Petri nets. The concrete XML-syntax is then defined by mapping the concepts of these UML meta models to XML elements. Currently, PNML is standardised as Part 2 of the International Standard ISO/IEC 15909 as the transfer syntax for three particular versions of Petri nets: Place/Transition-Nets, High-level Petri Nets, and Symmetric Nets. In this paper, we outline the concepts of PNML and, in particular, of the PNML Core Model and its mapping to XML-syntax. In order to illustrate the definition of a particular Petri net type, we discuss the meta model for Place/Transition-Nets. Since the exact details of the transfer syntax for High-level nets are not yet fixed, we do not go into the details of this Petri net type. Moreover, we report on the current state of the standardisation and possible future extensions, which might be included to Part 3 of ISO/IEC 15909.