StaBL

Abstract

Complexity of specification models of the present day have started becoming non-trivial. Hence, there is a need to evolve existing specification languages to support writing specifications following good coding practices such as incremental development and modularisation. Statechart is a modelling notation that has wide acceptance in the industry. To the best of our knowledge all current implementations of Statecharts have one common shortcoming: all Statechart variables are global. Global variables in a specification can lead to monolithic and fragile models which are hard to maintain and reuse. In this paper, we introduce local variables in Statecharts, motivate their use through illustrative examples, formalise their semantics, and analyse their interaction with basic Statechart features like hierarchical states, transitions and history. We have implemented this Statechart variant with local variables in a specification language called StaBL. Our case studies demonstrate significant improvement in modularity in models with local variable w.r.t those without local variables.