The working of a tool, Simulation Nets, for designing and executing models for simulation of systems is presented. The tool is an extension of the theoretically attractive Petri Nets, whose suitability in general simulation modeling has largely been overlooked in the simulation community. Simulation nets helps in obtaining a correct simulation model because of their good graphical properties, their strength in describing concurrent processes, and because of the possibility in proving correctness for some parts of the model by applying the well known reachability tree technique. The resulting graphical model consists of a number of submodels. The submodels are exact enough to permit simulation experiments to be performed without the need of programming. This permits easy incremental validation of the model, i.e., validation of the submodels and a hierarchy of coupled submodels. Simulation nets thus facilitates rapid modeling and experimentation and thus supports the decision maker in obtaining the data needed for him to make his decision. Experiences with a working prototype are presented.
