Devs Formalism and Methodology: Unity of Conception/diversity of Application

DEVS (Discrete Event System Specification) is a general modelling formalism with sound semantics founded on a system theoretic basis. This gives it a claim to be universal for formalisms describing Discrete Event Dynamic Systems (DEDS). This gives that any other formalism such as Petri nets, which have become very popular for DEDS control can be embedded in it. Moreover, DEVS extends to the continuous case thus facilitating combined discrete/continuous modelling. The universality of DEVS is significant because it has been implemented in a variety of simulation environments, as extensions of diverse underlying Object-Oriented languages such as CLOS and C++. This gives it not only the power of formal rigor but also the practical capability of application to real world complex systems. The DEVS formalism has associated with it a characteristic abstract simulation engine architecture that can be realized in diverse sequential and parallel/distributed platforms. It is especially suitable for the simulation study of complex technical and natural systems with intelligent components and for long term model development capability acquired through systematic reusability. This tutorial will present the basic concepts of the DEVS formalism and its associated simulation methodology. These concepts will be illustrated in the context of large scale ecosystems modelling.