Building complex models with LEGOs (Listener Event Graph Objects)

Event graphs are a simple and elegant language-independent way of representing a discrete event simulation (DES) model. In this paper we propose an extension to basic event graphs that enables small models to be encapsulated in reusable modules called listener event graph objects (LEGOs). These modules are linked together using a design pattern from object oriented programming called the "listener pattern" to produce new modules of even greater complexity. The modules generated in this way can themselves be linked and encapsulated, forming a hierarchical design which is highly scalable. These concepts have been implemented in Simkit, a freely available simulation package implemented in Java.