X-by-Construction: Towards Ensuring Non-functional Properties in by-Construction Engineering

Correctness-by-Construction engineering (CbC) is a refinement-based approach to develop functionally correct programs based on a formal specification. By correctly applying refinement rules during development, CbC enables detection of bugs during program construction, unlike post-hoc verification, which proves correctness only after implementation. Support for CbC engineering for non-functional properties is summarized under the term X-by-Construction (XbC). However, current XbC approaches are limited to information flow properties, leaving other non-functional properties of software quality, such as performance or reliability, unsupported. To address this gap, we present our vision for generalizing XbC to integrate non-functional properties into by-Construction engineering. In this way, we leverage the development of high-quality software through a refinement-based approach for future software engineering. With that, it will become possible to develop software ensuring that it not only exhibits functional correctness, but also non-functional guarantees by construction. Further, we propose ideas for ensuring energy efficiency in by-Construction engineering. We assess what it needs to integrate non-functional properties into by-Construction engineering and discuss arising challenges.