Executable object modeling with statecharts

Most object-oriented methods use a graphical notation, and most also adopt a state-based formalism to specify behavior. But most also fail to rigorously define the semantics of the languages they use to describe behavior. Without rigorous semantics, OO models can never be precise enough to produce fully executable models and enable automatic code synthesis. These issues are complicated and go beyond recommending a modeling approach or methodology-they are language design concerns, requiring rigorous mathematical underpinnings. Both syntax and semantics must be fully worked out: Any possible combination of constructs must be clearly characterized as syntactically legal or illegal, and each legal combination must be given a unique and formal meaning. In this article, the authors describe their integrated set of diagrammatic languages for object modeling built around statecharts and their supporting tool, Rhapsody, which produces a fully executable model and allows automatic code synthesis. As a result of the authors' collaboration with the team that defined the Unified Modeling Language, this language set and Rhapsody are consistent with UML.