An Improved Approach to Traceability in the Engineering of Complex Systems

Traceability is an essential technique in the engineering of complex, yet dependable systems. It informs on how an objective or a requirement at a given development phase is taken into account in subsequent phases. Traditionally, it is implemented using links relating the objective or requirement to its solution elements. However, in many cases, simple traceability links do not provide sufficient information. In particular, they do not explain the reasons of the chosen solution. Understanding these reasons is important for verification, but also for the renovation of the system long after its original designers are no longer available. This paper presents an improved traceability approach based firstly on the notion of justification framework, and secondly on an advanced requirements and solutions modelling framework. The approach not only relates requirements and solution elements as traceability links do, but also makes explicit the reasoning of the designers in the selection of the solution. The example given shows the refinement of a high-level functional objective that is easy to understand but not very precise. The approach shows how it is transformed into a more complete, more complex but unambiguous requirement, and explains the reasoning of the designers when specifying that requirement.