Reactive Petri Nets for Workflow Modeling

Petri nets are widely used for modeling and analyzing workflows

Piloteinsatz einer E-Assessment-Plattform für die grafische Modellierung

Die KEA-Mod-Plattform ermöglicht es, Modellierungsaufgaben mit verschiedenen Modellierungssprachen wie z.B. UML, Petri-Netzen, EPK oder BPMN durch Dozierende zu erstellen und von Studierenden bearbeiten zu lassen. Die Plattform kam in einer großen Lehrveranstaltung mit ca. 250 Studierenden zum Piloteinsatz. Die Studierenden konnten mit Hilfe der Plattform und des integrierten Modellierungswerkzeugs eine Aufgabenreihe mit Modellierungsaufgaben zu Petri-Netzen bearbeiten und einreichen. Anschließend erhielten die Studierenden automatisiert generiertes Feedback. Das Poster beschreibt die Evaluation dieses Piloteinsatzes aus der Perspektive der Studierenden und bietet erste Ergebnisse in Bezug auf die Plattform-Usability und zur wahrgenommenen Lernförderlichkeit des Feedbacks

Comparing Petri Net and Activity Diagram Variants for Workflow Modelling:A Quest for Reactive Petri Nets

Petri net variants are widely used as a workflow modelling technique. Recently, UMLa ctivity diagrams have been used for the same purpose, even though the syntax and semantics of activity diagrams has not been yet fully worked out. Nevertheless, activity diagrams seem very similar to Petri nets and on the surface, one may think that they are variants of each other. To substantiate or deny this claim, we need to formalise the intended semantics of activity diagrams and then compare this with various Petri net semantics. In previous papers we have defined two formal semantics for UMLact ivity diagrams that are intended for workflow modelling. In this paper, we discuss the design choices that underlie these two semantics and investigate whether these design choices can be met in low-level and high-level Petri net semantics. We argue that the main difference between the Petri net semantics and our semantics of UML act ivity diagrams is that the Petri net semantics models resource usage of closed, active systems that are non-reactive, whereas our semantics of UMLact ivity diagrams models open, reactive systems. Since workflow systems are open, reactive systems, we conclude that Petri nets cannot model workflows accurately, unless they are extended with a syntax and semantics for reactivity

A Graphical Query Language for Simulation Databases

In this paper we propose a graphical query language to analyse simulation runs which are stored in databases with a temporal dimension. A simulation run is a sequence of system states produced by discrete simulation. It may become very large such that manual analysis based on database browsing is not feasible anymore. Hence simulation databases require a specific query language to analyse the simulation data. Queries may be related to single states (e.g. Is there a state where condition c1 holds?) or to state sequences (e.g. Is there a state sequence, where first c1 holds, then c2 and finally c3?). An existing Petri net simulation environment has been extended to support the described concepts. Keywords Discrete simulation, simulation database, temporal data, graphical query language, Petri net 1. Introduction The goal of simulation is to investigate the behaviour of a system which already exists or is to be developed. Simulating system behaviour means to perform operations in a sim..

A global perspective of oral health : international health organizations, dental care delivery systems, and oral health goals for the year 2000

Thesis (M.Sc.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1991 (Dental Public Health).ix, 115 leaves : ill., mapsIncludes bibliographical references: (leaves 108-115).This project is designed to enhance interest in oral health globally. Three international aspects of oral health will be explored. International health organizations involved in the promotion and improvement of oral health globally are described. Dental care delivery systems of countries in various stages of socioeconomic and political development are discussed. The countries examined are China, Japan, New Zealand, the United Kingdom, and Venezuela. The “Global Goals for Oral Health in the Year 2000” shared by the World Health Organization and the Federation Dentaire Internationale are presented