Luc Touraille

A survey of modelling and simulation software frameworks using Discrete Event System Specification

Discrete Event System Specification is an extension of the Moore machine formalism which is used for modelling and analyzing general systems. This hierarchical and modular formalism is time event based and is able to represent any continuous, discrete or combined discrete and continuous systems. Since its introduction by B.P. Zeigler at the beginning of the eighties, most general modelling formalisms able to represent dynamic systems have been subsumed by DEVS. Meanwhile, the modelling and simulation (M&S) community has introduced various software frameworks supporting DEVS-based simulation analysis capability. DEVS has been used in many application domains and this paper will present a technical survey of the major DEVS implementations and software frameworks. We introduce a set of criteria in order to highlight the main features of each software tool, then we propose a table and discussion enabling a fast comparison of the presented frameworks. 1998 ACM Subject Classification I.6 Simulation and modeling

Refounding of the activity concept? Towards a federative paradigm for modeling and simulation

Currently, the widely used notion of activity is increasingly present in computer science. However, because this notion is used in specific contexts, it becomes vague. Here, the notion of activity is scrutinized in various contexts and, accordingly, put in perspective. It is discussed through four scientific disciplines: computer science, biology, economics, and epistemology. The definition of activity usually used in simulation is extended to new qualitative and quantitative definitions. In computer science, biology and economics disciplines, the new simulation activity definition is first applied critically. Then, activity is discussed generally. In epistemology, activity is discussed, in a prospective way, as a possible framework in models of human beliefs and knowledge.

Standardizing DEVS Model Representation

As discussed in the previous chapter, the idea of Standardizing DEVS model representation is to allow a platform-independent DEVS model representation to be executed by a DEVS-based simulator. In this case, a DEVS model is executed in a single processor or parallel/distributed simulation environment. This allows model reusability without the need for performing longdistance distributed simulation. Typically, models are stored in repositories and retrieved as needed. This type of interoperability is very important to achieve, because often modelers already have or can easily install a DEVS simulator on their machine. However, it is much more difficult for them to retrieve and reuse already existing models that were intended to run on a specific DEVS environment. Therefore, we need some way to provide access and share these numerous models. Having a platform independent DEVS model representation format allows us to go a step further in automatic model transformations and generate entire local copies of distant models.

Activity regions for the specification of discrete event systems

The common view on modeling and simulation of dynamic systems is to focus on the specification of the state of the system and its transition function. Although some interesting challenges remain to efficiently and elegantly support this view, we consider in this paper that this problem is solved. Instead, we propose here to focus on a new point of view on dynamic system specifications: the activity exhibited by their discrete event simulation. We believe that such a viewpoint introduces a new way for analyzing, modeling and simulating systems. We first start with the definition of the key notion of activity for the specification of a specific class of dynamic system, namely discrete event systems. Then, we refine this notion to characterize activity regions in time, in space, in states and in hierarchical component-based models. Examples are given to illustrate and stress the importance of this notion.