Modularization of Petri nets using object-oriented concepts

In the area of complex system design even the use of high-level Petri nets extended with substitutional constructs often results in models difficult to understand, maintain and extend. These problems, as well as a not satisfactory support for reuse of components, stem from the absence of capabilities to build Petri net models out of encapsulated modules. In order to overcome these limitations more sophisticated modularization techniques are needed. The extension of Petri nets with object-oriented concepts is a promising approach in this area, as these concepts offer well experienced and largely approved modularization capabilities. The paper gives a short overview of already existing proposals extending Petri nets with object-oriented concepts, pointing out why most of them provide no solution to the above stated deficiencies. To overcome the limitations of existing proposals a novel approach is presented, namely ´object-oriented predicate/transition nets´. Their application to software engineering is shown ranging from object design to visual programming.