Unambiguous UML Composite Structures: The OMEGA2 Experience

International audienc

Formal verification of LSC’s in the development process

Abstract. This paper presents how a model-based development process can be enhanced by the combination of using Live Sequence Charts (LSC) as the formal language to describe interactions together with automatic formal verification techniques that decide whether communication sequences are exhibitable or adhered to by the system. We exemplify our approach on the V-model, a widely used development process, considering a (Statemate) statecharts design of the reference case study “Funkfahrbetrieb ” (FFB) and discuss potential assets and drawbacks. We sketch a set of best practices on the use of LSC features and emphasise the possibilities for re-use of LSCs in the different activities of the development process. To give evidence for feasibility of automatic formal verification of LSCs, as well as its limitations, we present our approaches to the verification of possible and mandatory LSC requirements on Statemate models. We report experimental results we have obtained from formal verification of the FFB and briefly discuss the treatment of Statemate’s different notions of time.

Temporal logic for scenario-based specifications

Abstract. We provide semantics for the powerful scenario-based language of live sequence charts (LSCs). We show how the semantics of live sequence charts can be captured using temporal logic. This is done by studying various subsets of the LSC language and providing an explicit translation into temporal logic. We show how a kernel subset of the LSC language (which omits variables, for example) can be embedded within the temporal logic CTL ∗. For this kernel subset the embedding is a strict inclusion. We show that existential charts can be expressed using the branching temporal logic CTL while universal charts are in the intersection of linear temporal logic and branching temporal logic LTL ∩ CTL. Since our translations are efficient, the work described here may be used in the development of tools for analyzing and executing scenario-based requirements and for verifying systems against such requirements.