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Higher-Order object nets and their application to workflow modeling

: Löwe, M.; Wikarski, D.; Han, Y.

Berlin, 1995, 50 S.
Forschungsberichte - Technische Universität Berlin, Fachbereich 20 Informatik
Fraunhofer ISST ()
object nets; Objekt Netz; petri net; Petrinetz; workflow modeling

As more and more office work gets automated computer-aided, Thee demand for computer-aided cooperation and coordination energes and increases. It becomes a more apparent challenge to electronically provide all necessary information and suitable software tools to the right Person at tile right time for the right job. A workflow management system is a software tool dedicated to such tasks. Instead of being implicitly embedded in the application programs, processes in a workflow system should be explicitly described, managed and enacted in order to support system prototyping and evolution, and to facilitate coordinative and cooperative communication. To methodically support system analysis and to manage the complexity and concurrency,a conceptual model is needed. As such a model, Petri nets have extensively been used in process-entered environments. For modelling workflows, however, Petri nets and their variants still show some weaknesses. For instance, due to their inflexible structure, net models are rather incapable to cope with evolutionary or exceptional dynamics. Openness in nets and dynamic configuration are almost untouched issues. The mechanisms supporting abstraction and compositionality are still a weak point of the most net models proposed so far. In this paper we propose a new petri-net-based process modeling language: Higher-Order Object Nets that can better cope with some special modelin demands of workflow systems without loss of generality. After defining workflow systems and workflow management systems, and discussing some modeling demands with which traditional Petri nets have difficulties, we suggest the application of Higher-Order Objact Nets and also present some further developments, like w.r.t. Higher-Order Nets and Object Nets. We also investigate the connection of the object-oriented concepts to Petri nets. To describe the static structural aspects of application domains, and object model and an organization model are incorporated into our met hodology. Finally, based on the interpretation of Higher-Order Object Nets and Distributed Objact Computing (DOC), a workflow management system architecture is proposed. This paper is mainly conceptual. Its purpose is to introduce and discuss the features which, in our opinion, have to be included in the methodology for developing net-based workflow systems in order to make the methodology applicable in practical developments. Detailed specification of the methodology and complete formal definition of Higher-order Objact Nets will be given in subsequent reports.