An active database system executes actions automatically in response to events that are taking place either inside or outside the database. Developing an active database system, especially an active rule base, is not an easy task because some (unnoticed) errors may be introduced during its construction. In this paper, we present a Petri net-based approach to integrate active rules into traditional database system. We implemented our approach as a software system called ECAPNSim which not only has verification and simulation functionality but also allows us to develop multi-platform applications, i.e., a unique active rule base can work independently of the DBMS.