DFG-Forschergruppe Petri Net Technology

The extreme popularity of Business Process Management has two main effects concerning the requirements of process models: First, the circle of model designers and users has spread enormously. Especially, representatives from various administrative and technical departments who are not necessarily modeling experts are increasingly involved in the design of process models. As a consequence, the understandability of process models has gotten more important. Secondly, the number and variety of purposes process models are used for is going up. Besides the traditional use of process models within systems and software engineering these models are more and more used for organizational purposes like process reorganization, certification, activity-based costing (ABC) or human resource planing. Petri Nets could - from the methodical point of view - meet this demand for multiperspectivity. However, they are - despite of their capacity and long, worldwide recognition - widely judged as too "complex" for being used in Business Process Modeling (BPM). In contrast to multiperspectivity Petri Nets are often seen as an eletist specialist domain in which just mathematicia ns or engineers can understand and use their models. The Petri Net discussion is indeed dominated by syntactical and formal questions . Corresponding with this the quality of models is often just understood in terms of the accordance w ith syntactical rules or the fulfillment of mathematically provable and abstract dynamic properties. The core intended purpose of business process models is, however, to serve as a (graphical) communication basis for all involved persons for different purposes of modeling. In BPM is - with the effects sketched above - a different quality thinking demanded: For BPM-purposes it is not sufficient to deal with processes as sequences of states and state transitions on an abstract level supposing the relevance and usability is implicitly obvious. To use Petri Nets for BPM it is asked for concrete directions how to transform typical questions of Business Process Management in graphical models of good Fitness for Use. The Guidelines of Modeling (GoM) consist of design recommendations, whose application increase the semantic quality of information models beyond the accordance to syntactic rules. The GoM-framework includes six general guidelines which define quality categories of information models. These guidelines focus the correctness, the relevance, the economic efficiency, the clarity, the comparability, and the systematic design as the main quality criteria. The architecture of the GoM consists of levels and perspectives. Every general guideline (level 1) contains recommendations for different views (level 2, e.g. process models) and for different modeling techniques (level 3, e.g. Event-driven Process Chains (EPC) or PetriNets). Multiperspectivity meets differences in the requirements resulting from different objectives and different user related aspects (e.g. methodical background). Analysing the complexity perception relating to Petri Nets in terms of the GoM-Framework in the paper there is reflected on (non methodical) points which must be worked on for making Petri Nets more accurate for the purposes of BPM:

• Extracting the interesting out of Petri Nets in terms of BPM
• Making managers appreciate Petri Nets
• Guidelines of using Petri Nets

1. Towards a systematic and successive development of Pr/T-Nets a phase model will be presented. The views corresponding to the phase model are deduced from the Petri net specific understanding of processes. Within a view different aspects of describing process-structures and -instances are focused respectively.
2. Referring to analogies in the structures of Petri nets, which describe certain business and technology related objectives, structural model blocks will be presented. It will be shown how Petri-Nets can be designed more efficiently and of higher quality by composing these model blocks. The concept of structural model blocks abstracting from concrete operational contexts is set up complementary to existing model block concepts which depict concrete business processes. To make the application of the model blocks more operational they are assigned to the single phases.
3. In addition to syntactical aspects model conventions for Peti nets are given with the intention of achieving high semantic quality. The specific model conventions are integrated in the phase model as well. To show how these concepts can be put into practice a case study of an extensive Pr/T-Net based simulation project for optimizing a processes of a flexible manufacturing system will be presented.

Guidelines of Modelling - GoM: diverse publications, http://www-wi.uni-muenster.de/is/projekte/gom/.

v. Uthmann, C.; Becker, J.: Managing Complexity of Modeling Industrial Processes with Pr/T Nets. In: Proceedings of the IEEE International Conference on Systems, Man, and Cybernetics (SMC). San Diego, USA 1998.

v. Uthmann: Machen Ereignisgesteuerte Prozeßketten (EPK) Petrinetze für die Geschäftsprozeß- modellierung obsolet? In: EMISA FORUM Mitteilungen der GI-Fachgruppe "Entwicklungs- methoden für Informationssysteme und deren Anwendung", Heft 1/1998, S. 100-107.