Restructuring requirements specifications for managing inconsistency and change: a case study

The paper describes our experiences in restructuring multi perspective requirements specifications in order to identify and analyse inconsistencies and manage change. A partial, heterogeneous and reasonably large requirements specification from a NASA project was analysed and decomposed into a structure of "viewpoints", where each viewpoint encapsulates partial requirements of some system components described in the specification. Relationships between viewpoints were identified which included not only the interactions explicitly stated in the requirements but also some implicit and potentially problematic inter dependencies. The restructuring process and a first informal analysis of the resulting relationships enabled the detection of inconsistencies and the definition of some interesting domain dependent consistency rules. We believe that this restructuring into view points also facilitated requirements understanding through partitioning, and requirements maintenance and evolution through explicit identification of the inter viewpoint relationships.