Requirements evolution: from assumptions to reality

Requirements evolution is a main driver for systems evolution. Traditionally, requirements evolution is associated to changes in the users’ needs and environments. In this paper, we explore another cause for requirements evolu- tion: assumptions. Requirements engineers often make assumptions stating, for example, that satisfying certain sub-requirements and/or correctly executing cer- tain system functionalities would lead to reach a certain requirement. However, assumptions might be, or eventually become, invalid. We outline an approach to monitor, at runtime, the assumptions in a requirements model and to evolve the model to reflect the validity level of such assumptions. We introduce two types of requirements evolution: autonomic (which evolves the priorities of system al- ternatives based on their success/failure in meeting requirements) and designer- supported (which detects loci in the requirements model containing invalid as- sumptions and recommends designers to take evolutionary actions.