Writing and Correcting Textual Scenarios for System Design

1 The work presented in this paper is funded by the European Community within the framework of the ESPRIT LTR project CREWS (Cooperative Requirements Engineering With Scenarios) n°21903. Abstract Since a few years, scenarios have gained in popularity in Requirements Engineering. Textual scenarios are narrative descriptions of flows of actions between agents. They are often proposed to elicit, validate or document requirements. The CREWS experience has shown that the advantage of scenarios is their easiness of use, and that their disadvantage stands in the lack of guidelines for 'quality' authoring. In this article, we propose guidance for the authoring of scenarios. The guided scenario authoring process is divided into two main stages : the writing of scenarios, and the correcting of scenarios. To guide the writing of scenarios, we provide style and contents guidelines referring to a conceptual and a linguistic model of scenarios. Our assumption is that scenarios written in conformance to these guidelines can be semi-automatically analysed. Else, to guide the correcting of scenarios, we propose a set of enactable rules. These rules aim at the clarification, completion and conceptualisation of scenarios, and help the scenario author to improve his scenarios until acceptable quality in the terms of the former scenario models.