Requirements elicitation and validation with real world scenes

A requirements specification defines the requirements for the future system at a conceptual level (i.e., class or type level). In contrast, a scenario represents a concrete example of current or future system usage. In early RE phases, scenarios are used to support the definition of high level requi rements (goals) to be achieved by the new system. In many cases, those goal s can to a large degree be elicited by observing, documenting and analyzing scenarios about current system usage, i.e., the new system must often fulf ill many of the functional and nonfunctional goals of the existing system. To support the elicitation and validation of the goals achieved by the exis ting system and to illustrate problems of the old system, we propose to cap ture current system usage using rich media (e.g., video, speech, pictures, etc.) and to interrelate those observations with the goal definitions. Thus , we particularly aim at making the abstraction process which leads to the definition of the conceptual models more transparent and traceable. More precisely, we relate the parts of the observations which have caused t he definition of a goal or against which a goal was validated with the corr esponding goal. These interrelations provide the basis for: 1) explaining a nd illustrating a goal model to, e.g., untrained stakeholders and/or new te am members, and thereby improving a common understanding of the goal model; 2) detecting, analyzing, and resolving a different interpretation of the o bservations; 3) comparing different observations using computed goal annota tions; and 4) refining or detailing a goal model during later process phase s. Using the PRIME implementation framework, we have implemented the PRIME- CREWS environment, which supports the interrelation of conceptual models an d captured system usage observations. We report on our experiences with PRI ME-CREWS gained in a first experimental case study.