Modeling and Reasoning about Contextual Requirements: Goal-based Framework

Most of requirements engineering (RE) research ignores, or presumes a uniform nature of, the context in which the system operates. This assumption is no longer valid in emerging computing paradigms, such as Ambient, Pervasive and Ubiquitous Computing, where it is essential to monitor and adapt to an inherently varying context. There is a strong relationship between requirements and context. Context might be considered to determine the set of requirements relevant to a system, to derive the alternatives the system can adopt to reach these requirements, and to assess the quality of each alternative. A RE framework that explicitly captures and analyzes this relationship is still missing. Before influencing the behavior of software, context influences the behavior of users. It influences users' goals and their choices to reach these goals. Capturing this latest influence is essential for a software developed to meet users' requirements in different contexts. In this thesis, we propose a goal-oriented RE modeling and reasoning framework for systems operating in and reflecting varying contexts. To this end, we develop a conceptual modeling language, the \emph{contextual goal model}, that captures the relationship between context and requirements at the goal level and provides constructs to analyze context. We develop a set of reasoning mechanisms to analyze contextual goal models addressing various problems: the consistency of context, the derivation of requirements in different contexts, the detection of conflicts between requirements happening as a consequence of changes in the context they lead to, and the derivation of a set of requirements that leads to a system developed with minimum costs and operable in all of the analyzed contexts. We develop a formal framework, CASE tool, and methodological process to assist analysts in using our modeling and reasoning RE framework. We evaluate our proposed RE framework by applying it on two systems: smart home for patient with dementia and museum-guide mobile information system. Our contribution to RE research is a RE framework specialized for emerging computing paradigms that weave together software and context. It allows us to overcome the limitation of existing RE frameworks that ignore, or presume a uniform nature of, the context in which the system operates.