Object Composition in Scenario-Based Programming

We investigate the classical notion of object composition in the framework of scenario-based specification and programming. We concentrate on live sequence charts (LSC), which extend the classical partial order semantics of sequence diagrams with universal/existential and must/may modalities. In order to tackle object composition, we extend the language with appropriate syntax and semantics that allow the specification and interpretation of scenario hierarchies – trees of scenarios – based on the object composition hierarchy in the underlying model. We then describe and implement a composition algorithm for scenario hierarchies, and discuss a trace-based semantics and operational semantics (play-out) for the extension. The extension has been fully implemented, and the ideas are demonstrated using a small example application.