Petri Net Modules

Here we present a new module concept for Petri nets that is based on the component concepts of Continuous Software Engineering (CSE). According to that concept two distinguished interfaces are required. These are import and export interfaces. The import describes the assumptions on the environment, e.g. in terms of used components. The export gives an abstraction of the functionality and presents e.g. the offered services. The modules for Petri we introduce here consist of three nets for the import, the body of the module and the export. The import net IMP states the prerequisites the modules assumes. The body net BOD represents the internal functionality. The export net EXP gives an abstraction of the body that can be used by the environment. We provide module operations to compose larger modules from basic ones. Operations to compose Petri net modules are crucial as the main purpose is composition. In most approaches module concepts come along with just one operation. A great advantage is achieved having different possibilities to compose modules, as it increases the convenience of modeling large systems. We propose three different operations, composition, disjoint union, and union. Our main result in this contribution is that these module operations are compatible with each other.