Requirements and Specification Exemplars

Specification exemplars are familiar to most software engineering researchers. For instance, many will have encountered the well known library and lift problem statements, and will have seen one or more published specifications. Exemplars may serve several purposes: to drive and communicate individual research advances; to establish research agendas and to compare and contrast alternative approaches; and, ultimately, to lead to advances in software development practices. Because of their prevalence in the literature, exemplars are worth critical study. In this paper we consider the purposes that exemplars may serve, and explore the incompatibilities inherent in trying to serve several of them at once. Researchers should therefore be clear about what successfully handling an exemplar demonstrates. We go on to examine the use of exemplars not only for writing specifications (an end product of requirements engineering), but also for the requirements engineering process itself. In particular, requirements for good requirements exemplars are suggested and ways of obtaining such exemplars are discussed.