Towards Multi-layered Temporal Models: A Proposal to Integrate Instant Refinement in CCSL

Part 1: Full Papers ; Part of the book sub series: Programming and Software Engineering (LNPSE); International audience; For the past 50 years, temporal constraints have been a key driver in the development of critical systems, as ensuring their safety requires their behaviour to meet stringent temporal requirements. A well established and promising approach to express and verify such temporal constraints is to rely on formal modelling languages. One such language is CCSL, first introduced as part of the MARTE UML profile, which allows the developer, through entities called clocks, to abstract any system into events on which constraints can be expressed, and then assessed using TimeSquare, a tool which implements its operational semantics. By nature, CCSL handles horizontal separation (component based design at one step in the system development) of concerns through the notion of clocks, but does not yet take into account the other major separation of concerns used in modern system development: vertical separation, also called refinement in the literature (relations between the various steps of the system development). This paper proposes an approach to extend CCSL with a notion of refinement in order to handle temporal models relying on both vertical and horizontal parts. Our proposal relies on the notion of multi-layered time to provide two new CCSL relations expressing two different yet complementary notions of refinement. Their integration with the other CCSL constructs is discussed and their use is illustrated while the relevance and future impacts of this extended version of CCSL is detailed.