Jörn Freiheit

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The design of real-time systems requires modeling and analysis techniques, to ensure their correct and timely operation. In many cases a realistic model should be able to cover both fixed and stochastic times. Stochastic Petri nets are a promising description technique in this field, but mixing deterministic and randomly distributed times in one model makes(More)
Petri nets are useful for modelling complex concurrent systems. While modelling using Petri nets focusses on local states and actions , the analysis methods are concerned with global states and their transitions. Unfortunately generation of the complete state space suffers from the well-known state space explosion problem. This paper presents a method to(More)
In this paper an aggregation technique for generalised stochastic Petri nets (GSPNs) possessing synchronised parallel structures is presented. Parallel processes featuring synchronisation constraints commonly occur in fields such as product assembly and computer process communications, however their existence in closed networks severely complicates(More)
In this paper we bridge the gap between performance evaluation and the modelling of business processes. On the basis of a case study from the field of operational planning processes we investigate the performance evaluation of human resource management processes. In particular we consider the affect of timing in operational planning processes. We use(More)
Not only since the upcoming of Service-oriented Architectures the modelling of cross-organizational business processes is a heavily investigated field comprising dozens of standards based on different concepts. New techniques on the implementation site, e.g. Web Service orchestration and choreography, further extended the possibilities and requirements on(More)
The paper discusses the usability concept of workflow services for event-driven process chains. Usability is similar to controllability, known from Workflow net based BPEL semantics theory. Based on the observation, that if business processes interact (for instance because one of them is a service), it must be possible to check whether this is structurally(More)