Representing and Elaborating Quality Requirements: The QRA Approach

Requirements Engineering (RE) is arguably one of the most critical activities in the lifecycle of a software-centric system. In traditional RE techniques where more emphasis is placed on systematic upfront analysis, the tendency is to focus mostly on functionality rather than quality issues. Such a focus remains the same in Agile methods, except that emphasis has been shifted to delivering executable code quickly. Therefore, both traditional RE and Agile methods have failed to use quality requirements (QRs) as a guiding principle to designing appropriate software architectures. This paper presents the quality requirements analysis (QRA) approach to representing and elaborating QRs alongside FRs. The QRA approach integrates functional modeling of goals and business processes with QRs and provides the means for elaboration of key quality factors through a set of quantitative formulae. This paper describes QRA’s conceptual foundations and illustrates them through a real world stock trading system relating to business processes of an international financial firm.