A conceptual framework for state-based and event-based formal behavioural specification languages

We introduce a simple conceptual framework for assessing a number of well known formal specification techniques w.r.t. their ability to model state-oriented and/or event-oriented aspects of system behaviour. By attributing a-priori equal importance to the notions of event and state, by explicitly recognizing the two derived, fundamental ways of thinking about system behaviours, and by assessing the bias of existing formal methods towards one or the other, one can make more conscious choices in the upper phases of software development, that is, in requirements elicitation and analysis, in the construction of abstract system models, and in the choice of formal languages for high- and low-level design. In particular, we assess the recently introduced model of Abstract State Processes, and the design choices behind its definition, in light of the introduced state-event framework.