From UML State Charts to DEVS State Machines using XML

Arizona Center for Integrative M&SECE Department, University of ArizonaTucson, AZ 85721AbstractModeling and Simulation (M&S) for system design and prototyping is practiced today both in the industryand academia. Modeling and Simulation are two di erent areas altogether and have speci c objectives.However, most of the times these two separate areas are taken together. The developed code is tightly wovenaround and model and the underlying simulator that executes it. This constraints both the developmentof model as well as the simulation engine and impacts scalability of the developed code. Modeling is moreart than science and the level of abstraction plays a crucial role in model’s performance. Furthermore, it isdicult to develop a model because it needs both domain knowledge and simulation techniques, which alsorequires communication among users and developers. UML is the preferred method used today in industry,but it lacks simulation power. Discrete Event Speci cation (DEVS) based modeling that separates themodel and the simulator, provides a cleaner methodology to develop models. However DEVS today is usedby engineers who understand discrete event modeling at a much detailed level and are able to translaterequirements to DEVS modeling code. It is oblivious to industry practitioners that use UML due to itsgraphical expressive power. There have been earlier e orts to integrate UML and DEVS but they haven’tsucceeded in providing a transformation mechanism due to inherent di erences in these two modelingparadigms. DEVS state machines are more expressive than UML state machines, require more information,speci cally nite timeouts for each state. This paper presents an integrated approach towards using UMLstate machines transformed as DEVS models. The transformation mechanism is available as an upcomingstandard, State Chart XML (SCXML) that provides a generic execution environment based on CCXML andHarel State tables. We will illustrate the transformation by taking a UML state machine and augmentingit with information during the process using SCXML to make it DEVS capable. Further, we will also showthat the obtained DEVS models belong to a speci c class of DEVS models called Finite Deterministic DEVS(FD-DEVS) that is available as a W3C XML schema.Keywords: DEVS, FD-DEVS, UML-based Modeling, XML, Model Transformation