Deducing Requirements From Agile Software Processes

Abstract

In classical engineering practice, the elicitation of requirements is an important early project phase. Requirements help to define the project goals and scope, they serve as a basis for cost estimation, and in validated projects they are the cornerstone of the traceability matrix. However, requirements elicitation is difficult because of the abstract nature of the process and because there is uncertainty at the start of a project about what can be done. In recent software development practice, waterfall methods have fallen into disfavor, and agile methods are preferred. Agile methods avoid formal requirements specification, and instead use techniques such as scrums and user stories to specify development phases that are performed iteratively. In agile methods, requirements remain implicit and undocumented. While agile may avoid the difficulties of formal elicitation of requirements, it may in the process bypass the activity of analysis of user needs, and the generation of a baseline against which the implemented system can be validated. In this thesis we show that requirements can be deduced from the user stories and process maps that result from agile methodologies. A modified failure mode effects analysis approach is used to identify risks, failure modes, and countermeasures, and to evaluate risks and countermeasures by computing severity and likelihood of the risks, and the benefits of the countermeasures. The deduction of requirements from agile artifacts encourages an agile team to think through its preferences and proposed implementations, and objectively rate them. It captures the rationale for the user stories and process maps, and provides traceability from business goals to the functional requirements.