A PROPOSAL FOR A SCENARIO CLASSIFICATION FRAMEWORK 1

The Requirement Engineering, Information Systems and Software Engineering communities recently advocated scenario-based approaches which emphasise the user/system interaction perspective in developing computer systems. Use of examples, scenes, narrative descriptions of contexts, mock-ups and prototypes, all these ideas can be called scenario based approaches, although exact definitions are not easy beyond saying these approaches emphasise some description of the real world. Experience seems to tell us that people react to 'real things' and that this helps clarifying requirements. Indeed the widespread acceptance of prototyping in system development points to the effectiveness of scenario based approaches. However, we have little understanding about how scenarios should be constructed, little hard evidence about their effectiveness and even less idea about why they work. The paper is an attempt to explore some of the issues underlying scenario based approaches in Requirements Engineering (RE) and to propose a framework for their classification. The framework is a 4-dimensional framework which advocates that a scenario-based approach can be well-defined by its form, contents, purpose, and life cycle. Every dimension is itself multi-faceted and a metric is associated to each facet. Motivations for developing the framework are threefold : (a) to help understanding and clarifying existing scenario based approaches, (b) to situate the industrial practice of scenarios and (c) to assist researchers develop more innovative scenario based approaches.