A UML Profile for Designing Reusable and Verifiable Software Components for On-Board Applications

Software frameworks offer sets of reusable and adaptable components embedded within an architecture optimized for a given target domain. This paper introduces an approach to the design of software frameworks for on-board applications taken in the ASSERT project. Onboard applications are characterized by functional and non-functional (timing, in particular) requirements. The proposed approach separates the treatment of these two aspects. For functional issues, it defines an extensible state machine concept to define components that encapsulate functional behaviour and offer adaptation mechanisms to extend this behaviour while warranting the preservation of the functional properties defined at the level of the framework. For timing issues, it defines software structures which are provably endowed with specific timing properties and which encapsulate functional activity in a way that enforces them. A UML2 profile is defined to formally capture both the state machine concept and the real-time structures. The profile allows the proposed approach to be enforced at design level. We are using our approach to construct a software framework for satellite on-board applications.