Requirements-Driven Qualitative Adaptation

Coping with run-time uncertainty pose an ever-present threat to the fulfillment of requirements for most software systems (embedded, robotic, socio-technical, etc.). This is particularly true for large-scale, cooperative information systems. Adaptation mechanisms constitute a general solution to this problem, consisting of a feedback loop that monitors the environment and compensates for deviating system behavior. In our research, we apply a requirements engineering perspective to the problem of designing adaptive systems, focusing on developing a qualitative software-centric, feedback loop mechanism as the architecture that operationalizes adaptivity. In this paper, we propose a framework that provides qualitative adaptation to target systems based on information from their requirements models. The key characteristc of this framework is extensibility, allowing for it to cope with qualitative information about the impact of control (input) variables on indicators (output variables) in different levels of precision. Our proposal is evaluated with a variant of the London Ambulance System case study.