Modeling and Analyzing Contextual Requirements

The relation between contexts and requirements can be very complex to analyze. A context can motivate a requirement, a requirement can be satisfied only in a specific context, and a context can influence the quality of each possible alternative of satisfying a requirement. To capture and deeply understand this relation, we need to start from the reasons of a requirement, namely stakeholders goals, and analyze at this level the system variability with respect to the context. In this paper, we propose a goal-based approach to model and analyze contextual requirements. We adopt Tropos goal modeling framework where we introduce contextual variation points and provide a set of constructs to hierarchically analyze contexts. We also articulate a new problem, the context interaction problem; we study its influence on both monitoring and functional requirements, and we finally provide a SAT-based approach to deal with it. We show the process for creating our models and illustrate our approach on a museum-guide scenario.