A Systematic Identification of Formal and Semi-Formal Languages and Techniques for Software-Intensive Systems-of-Systems Requirements Modeling

Software-intensive systems-of-systems (SoS) refer to an arrangement of managerially and operationally independent systems (i.e., constituent systems), which work collaboratively toward the achievement of global missions. Because some SoS are being developed for critical domains, such as healthcare and transportation, there is an increasing need to attain higher quality levels, which often justifies the additional costs that can be incurred by adopting formal and semi-formal approaches (i.e., languages and techniques) for modeling requirements. Various approaches have been employed, but a detailed landscape is still missing, and it is not well known whether these approaches are appropriate for addressing the inherent characteristics of SoS. The main contribution of this paper is to present this landscape by reporting on the state of the art in SoS requirements modeling. This landscape was built by means of a systematic mapping and shows formal and semi-formal approaches grouped from model-based to property-oriented ones. Most of them have been tested in safety-critical domains, where formal approaches such as finite-state machines are aimed at critical system parts, whereas semi-formal approaches (e.g., unified modeling language and i*) address non-critical parts. Although formal and semi-formal modeling is an essential activity, the quality of SoS requirements does not rely solely on the formalism that is used, but also on the availability of supporting tools/mechanisms that enable, for instance, requirements verification along the SoS life cycle.