Integrating a Neutral Action Language in a DEVS Modelling Environment

Visual environments for the modelling and simulation of complex, software-intensive systems are increasingly popular. While visual languages have many advantages, they may not be appropriate to render all details of a Discrete EVent system Specification (DEVS) model. Textual may be more appropriate, both to completely describe all details of a DEVS model, and to make the specification independent of the implementation platform. In this paper, we propose two textual notations that are used as part of an integrated modelling and simulation environment for the Parallel DEVS formalism. Both notations allow the specification of DEVS functions by means of neutral action code. DEVSPro uses Python-like textual syntax and supports the full power of Parallel DEVS. From this neutral specification, simulator-specific code is synthesized. DEVSLang supports blended textual/visual modelling. It is more restricted in expressiveness to match the limited expressiveness of visual notations. For example, the sequential states in an Atomic model must be explicitly enumerated. Visual DEVSLang models are transformed to their textual form in order to carry out syntactic and semantic checks. Possible detected errors are fed back to the visual modelling environment allowing the modeller to make changes directly in the source model. DEVSLang models are further translated automatically to DEVSPro models to allow for possible combination with DEVSPro models and subsequent analysis and simulation.