In: Proceedings of the 14th International Congress on Cybernetics, Namur, Belgium, pages 453-458. International Association for Cybernetics, August 1995.
Abstract: Todays complex systems require both, methods for their easy modeling and tools for their efficient handling on computer systems. The language developed by us for those often contradictory goals - easy modeling, abstraction, and reusability must be provided to the user and efficient execution must be achieved on a computer - is based on a class of hierarchical object-oriented Petri nets with time inscriptions and is called THORNs (Timed Hierarchical Object-Related Nets).
In this paper, the concepts of the THORN simulation language are explained. First, a subclass of THORNs without time or hierarchy aspects is described. Though already quite powerful, the language defined this way offers no concepts to model time aspects of the system, e.g. the duration or starting time of an activity. Those disadvantages are mastered by introducing the time concepts of THORNs. The achieved sublanguage of THORNs has left one major drawback: it lacks the possibilities to reuse models already written, to model various similar or equal complex parts of the system in an appropriate and easy way, and to simply organize a model according to the physical or logical structure of a system. All those shortcomings disappear by introducing hierarchical concepts into the defined subclass, extending it to the full class of THORNs.
The presentation of the THORN language is illustrated by small examples.