DFG Forschergruppe Petri Net Technology (PNT) sponsored by the Deutsche Forschungsgemeinschaft (DFG)

Results of NSE

The NSE group of Prof. Weber focuses on the Petri net based software development. In the first phase of the project, the group's activities centered on Petri net based development of application software for business process support. In this context, particular attention was devoted to business process modeling and the development of workflow applications for software based business process support. The reference application used was a workflow application for the management of real estate as part of a housing information system (WWIS).

The main research areas and results of the first project phase are given below:

1. »Petri net Baukasten« conception.

(Joint acitivity of NSE, TheoPAn and UBS) The conception of the »Petri net Baukasten« is based on a view concept corresponding to its various uses and objectives see [Web97,BFG+98]. The Application Developer View supports the choice of suitable Petri net techniques for the development of a given application. The Expert View gives precise descriptions of Petri net techniques in formal, constructive terms. The Tool Developer View helps to provide or to develop Petri net tools enabling practical use of Petri net techniques. Each view describes those aspects of the »Petri net Baukasten« which are relevant to the specific users, all three views are related to the so called Common Base. The Common Base is a Petri net classification in which the Petri net types on which various Petri net techniques are based are described according to their specific features and linked via specialization/generalization relations.

2. Process models for net based software development.

In conventional process models, different techniques are used for different phases of systems development. [Bor96] examines the ability of various Petri net techniques to adequately describe two important results of the development process (requirements specification and system architecture).

The descriptive power of various Petri net techniques was measured against the requirements for these two items. These tests were accompanied by an example from the field of process automation. Particular attention was paid to the transition from a Petri net based description of the requirements to a description of the system architecture based on high-level Petri nets.

The process model forming the basis for development of the reference application `WWIS Real Estate Management' was also examined, see [Lem96]. This is a process model for integrated development of workflow applications based on the FUNSOFT approach [DG94] supported by the LEU development environment.

3. Module concept for Petri nets.

Acceptance of Petri nets in industry depends heavily on the extent to which they are able to successfully deal with the complexity of large systems. In this context, [Fri97a] transferred the well known module concept based on the data encapsulation and data abstraction from the field of software engineering to high-level Petri nets. In addition, the example of `the hurried philosophers' [Sib96] was used to show how autonomous, communicating objects can be modeled using high-level Petri nets [Fri97b].

4. Higher-Order Object Nets (HOON).

To improve the flexibility of net based workflow models, the Higher-Order Object Nets approach was developed which enables the systematic management of workflow resources linked to workflow models [Han97]. These workflow resources include workflow models (HOONs), software systems, roles and persons, as well as data and documents.

5. Parameterized Petri net type.

In cooperation with the UBS group, the parameterized Petri net type PARFUN was developed with one formal parameter for each individual aspect of the organizational or data structure to be specified [EGLP97,EGL+97,GLP96]. By selecting different actual parameters, variants of this (abstract) Petri net type can be created, all of which support the practice oriented concepts of the FUNSOFT approach [Gru91] to a great extent. The instantiation with extended entity/relationship diagrams and a tree like organizational structure therefore essentially corresponds to the FUNSOFT approach on which the above mentioned WWIS system is based. The various instantiations of PARFUN is dealt with in [GL98,GL99], with the emphasis on parameters describing aspects of the data structure.

6. Comparison of Petri net tools.

Based on a series of assessment criteria [Wik96] and [Wik97] compared over 50 tools for Petri net editing, analysis, simulation, generation, etc. This comparison was based on two classes of criteria: technical/functional criteria and socially assessable criteria.

[BFG+98]
Alexander Borusan, Olaf Fricke, Maike Gajewsky, Ekkart Kindler, Sabine Lembke, Julia Padberg, Tobias Vesper, Herbert Weber, and Michael Weber, Foundation Concepts of the »Petri Net Baukasten«, 1998, http://www.informatik.hu-berlin.de/PNT/pnt-public.html.

[Bor96]
Alexander Borusan, Requirements on Petri Net Technique from Point of View of System Development Process, Kick-Off-Workshop der DFG-Forschergruppe Petrinetz-Technologie, (Hartmut Ehrig, Wolfgang Reisig, and Herbert Weber, eds.), no. 73, July 1996, pp. 1-9.

[DG94]
W. Deiters and V. Gruhn, The FUNSOFT Net Approach to Software Process Management, International Journal of Software Engineering and Knowledge Engineering, vol. 4 (1994), no. 2, 229-256.

[EGL+97]
Hartmut Ehrig, Maike Gajewsky, Sabine Lembke, Julia Padberg, and Volker Gruhn, Reverse Petri Net Technology Transfer: On the Boundary of Theory and Applications, Move-On-Workshop der DFG-Forschergruppe Petrinetz-Technologie (Technische Universität Berlin) (Hartmut Ehrig, Wolfgang Reisig, and Herbert Weber, eds.), no. 97-21, April 1997, pp. 7-28.

[EGLP97]
H. Ehrig, M. Gajewsky, S. Lembke, and J. Padberg, Reverse Petri Net Technology Transfer: On the Boundary of Theory and Application, Formal Methods Pacific '97 (Lindsay Groves and Steve Reeves, eds.), Springer-Verlag Singapore Pte. Ltd, 1997.

[Fri97a]
Olaf Fricke, Data Encapsulation and Data Abstraction with Petri Nets - a graphical Visualization of Modules, Petri Nets in System Engineering (PNSE'97), (Berndt Farwer, Daniel Moldt, and Mark-Oliver Stehr, eds.), no. 205, September 1997, pp. 151-163.

[Fri97b]
Olaf Fricke, Petrinetze für die Modellierung kommunizierender selbst-aktiver Objekte, Vortrag im gemeinsamen Forschungskolloquium der Fachgruppe CIS/TU Berlin und des Fraunhofer ISST, Technische Universität, Berlin, 8. December 1997.

[Gru91]
Volker Gruhn, Validation and Verification of Software Process Models, Dissertation, University Dortmund, 1991.

[GL98]
Volker Gruhn and Sabine Lembke, Integration of Petri Net Based Process Description with Different Data Modelling Techniques, Proceedings of The Third Biennial World Conference on Integrated Design and Process Technology (M.M. Tanik, J. Tanaka, K. Itoh, M. Goedicke, W. Rossak, H. Ehrig, and F. Kurfess, eds.), vol. 4, Society for Design and Process Science, 1998, Berlin, Germany, July 6-9, 1998, pp. 105-112.

[GL99]
Volker Gruhn and Sabine Lembke, Flexible Integration of Petri Net Based Process Description with User-Specific Data Descriptions, Journal of Integrated Design and Process Technology (1999), To appear.

[GLP96]
M. Gajewsky, S. Lembke, and J. Padberg, Parametrisierung von FunSoft-Netzen für die flexible Modellierung von Workflow-Modellen, Kick-Off-Workshop der DFG-Forschergruppe ``Petrinetz-Technologie'' (Humboldt-Universität zu Berlin) (H. Weber, H. Ehrig, and W. Reisig, eds.), Informatik-Bericht 73, 1996.

[Han97]
Yanbo Han, Software Infrastructure for Configurable Workflow Systems - A Model-Driven Approach Based on Higher-Order Object Nets and CORBA, Dissertation, Technische Universität Berlin, Wissenschaft & Technik Verlag Berlin, 1997.

[Lem96]
Sabine Lembke, Anwendungsentwicklung in der LION-Entwicklungsumgebung (LEU), Kick-Off-Workshop der DFG-Forschergruppe Petrinetz-Technologie (Hartmut Ehrig, Wolfgang Reisig, and Herbert Weber, eds.), no. 73, July 1996, pp. 72-81.

[Sib96]
C. Sibertin-Blanc, The Hurried Philosophers, Proposal for a case study for the 2nd workshop on `Object-Oriented Programming and Models of Concurrency', Osaka 1996.

[Web97]
Herbert Weber, The »Petri Net Baukasten« Foundation Concept, Move-On-Workshop der DFG-Forschergruppe Petrinetz-Technologie (Technische Universität Berlin) (Hartmut Ehrig, Wolfgang Reisig, and Herbert Weber, eds.), April 1997, pp. 153-165.

[Wik96]
Dietmar Wikarski, Petri Net Tools: a Comparative Study, ISST-Bericht Nr. 39, Fraunhofer ISST, Berlin, 1996.

[Wik97]
Dietmar Wikarski, Petri Net Tools: A Comparative Study, Forschungsbericht des Fachbereichs Informatik Nr. 97-4, Technische Universität Berlin, 1997.