Abstract

Developing high quality requirements specifications is mandatory for a number of critical industrial systems. The KAOS goal-driven methodology has been designed to elicit and validate requirements and also to prove their consistency. This methodology has been successfully implemented in two integrated tools (Objectiver and FAUST) and has been validated in many industrial projects. All of these have shown how the quality of the requirements can be improved with KAOS/Objectiver due to the following factors:- a rigorous reasoning and decision making on the requirements,- the constructive nature of the goal-oriented method,- the tracing facilities automatically generated between properties and specifications, and- the automatic generation of reports based on the goal- oriented structure of the requirements. Another contribution to the quality of requirements is the tight integration between informal requirements and formalised requirements. One the one hand, the KAOS methodology allows the analyst to give a complete informal description of the specification. On the other hand, the FAUST extensions of the Objectiver environment allows to describe and analyse the formal aspects of the specification by making use of some of the best formal tools hidden behind the stakeholder view on the requirements. A recent report from the Standish Group estimates that a staggering 40 percent of all software projects fails. To a large degree, these failures are linked to requirements- either they are incorrectly defined from the

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