This paper addresses the broad topic area of cross-paradigm simulation modeling with a focus on the discrete-event, system dynamics and agent-based paradigms. It incorporates contributions from four panel members with diverse perspectives and areas of expertise. First, each paradigm is described and definitions are presented. The difference between the process-oriented worldview and the event-oriented worldview within discrete-event simulation modeling, and the importance of this difference for crossparadigm modeling, are discussed. Following the definitions, discussion of cross-paradigm modeling is given for each pair of these paradigms, highlighting current challenges and early successes in these areas. The basic time-advance mechanisms used in simulation modeling are also discussed, and the implications of these mechanisms for each paradigm is explored. 2788 978-1-4577-2109-0/11/$26.00 ©2011 IEEE Heath, Brailsford, Buss, and Macal  In this section we present a brief description of DES, SD, and ABS. The important distinction between two main DES worldviews is also highlighted. Discrete-event simulation (DES) is a modeling method for stochastic, dynamic models where simulation state variables change at discrete points in time. The discrete point in time when one or more state variables change is termed and event. Strictly speaking, therefore, DES does not include variables that change continuously with respect to time. DES is a highly flexible approach in which almost anything can be coded; models can be incredibly detailed. Most commercial DES software has a graphical interface which allows the user to see the system operating on the screen, which in some cases is almost like watching a movie. This can be a very powerful communication aid for non-technically minded clients. Because of stochasticity, multiple replications of simulation runs are required to obtain statistically significant results. Although the above definition is the commonly accepted definition of DES, there are two different worldviews that dominate DES modeling today: a process-oriented worldview and an event-oriented worldview. It turns out that these worldviews matter when it comes to addressing the challenges of crossparadigm simulation modeling, so we will present a basic description of each. Although the eventoriented worldview appears to have come first, the process/resource worldview seems much more common today, so it will be presented first. The process-oriented worldview for DES generally consist of describing entities which move through various processes, where each process requires one or more resources and takes a certain (usually stochastic) amount of time. Figure 1 shows a typical depiction showing an entity e moving through process A. The first event would be the arrival of e to A's queue, followed by the event of the resource(s) required by A beginning processing e, and ending with the event of the completion of the processing of e.
Heath et al. REF presented an interesting discussion about cross-paradigm simulation modeling.
Cross-paradigm simulation modeling: challenges and successes
WSC '11
Computer Science