Modeling Adaptive Reactive Systems

Reactive systems have been described by means of several notations and formalisms, through which different orthogonal aspects are captured: their internal state behavior, their synchronization aspects and their communication component. Classical formalisms are intended in a large extent to capture static aspects of systems behavior. However, for systems which change dynamically in response to external stimuli, that approach is not enough to represent all its features, because of the lack of ability of classical models to easily describe dynamic changes in the systems behavior. In order to fulfill this requirement, an adequate model for representing dynamically changing systems should be based on some kind of formal device having the feature of representing self-modifications. We call adaptive such a class of formal devices, and the technology they allow to implement. In the following sections some adaptive devices are described as a qualitative introduction to the modeling of adaptive reactive systems. As an illustration, a very simple reactive system with adaptive properties is described by means of adaptive statecharts: an interactive system for decompressing 2-D packed sequences based on geometric shapes moving on a plane allowing the user to disturb the exhibition of the sequence by modifying shape locations during its presentation. In this paper we explore the concepts of adaptive technologies applied to the modeling of reactive systems. In particular, adaptive automata and adaptive statecharts are considered. [1], [8]