The FoReVer Contract-Based Approach

The development of complex computer-based systems poses two fundamental challenges. On one side, the architectural decomposition must be complemented by a suitable refinement of the requirements. On the other side, it is fundamental to provide the means for component reuse in order to limit development costs. In this chapter, the authors discuss the approach taken in FoReVeR, a project funded by the European Space Agency (ESA), where these two issues are tackled in the setting of space systems. The approach taken in FoReVeR is based on the idea of contracts, which allow one to formally specify the requirements of components at different levels of abstraction and to formally prove the correctness of requirements decomposition. In particular, the authors show how system-level requirements can be progressively refined into software requirements and how the contract-based framework supports the reuse of the components of a reference architecture under development by ESA. The authors discuss how the proposed solution has been integrated in a space development process and present the results of case studies.