Modeling UML Object Event Handling with Petri Nets

W. Szmuc, T. Szmuc (AGH Univ. of Science and Techn., Poland)

The paper describes method of formal modeling object event handling as it is implemented in UML. The resulted Petri net allows to check UML model properties not only by simulation but also formally. For possibly closest congruence between UML and Petri net model an event queue is defined. Each state machine assigned to an object has its own event queue which is available as long as the machine is. That allows to model not only a simple message passing but also cases, when state machine cannot handle an event. A higher priority of sub-machine's event queue was also taken into consideration. The presented solutions are part of bigger conversion algorithm from UML model to Petri nets. However, the paper was intended to describe the issue in such a detailed way it could be used outside the whole algorithm.