The University of Sussex

Using ViewPoints for inconsistency management

Steve Easterbrook, Bashar Nuseibeh

Large-scale software development is an evolutionary process. In an evolving specification, multiple development participants often hold multiple, inconsistent views on the system being developed, and considerable effort is spent handling recurrent inconsistencies. Detecting and resolving inconsistencies is only part of the problem: a resolved inconsistency might not stay resolved as a specification evolves. Frameworks in which inconsistency is tolerated help by allowing resolution to be delayed. However, the evolution of a specification may affect both resolved and unresolved inconsistencies. We present and elaborate a framework in which software development knowledge is partitioned into multiple views called 'ViewPoints'. Inconsistencies between ViewPoints are managed by explicitly representing relationships between them, and recording both resolved and unresolved inconsistencies. We assume that ViewPoints will often be inconsistent with one another, and we ensure that a complete work record is kept, detailing any inconsistencies that have been detected, and what actions, if any, have been taken to resolve them. The work record is then used to reason about the effects of subsequent changes to ViewPoints, without constraining the development process. The paper demonstrates how inconsistency management is used as a tool for requirements elicitation, and how ViewPoints provide a vehicle for achieving this. Inconsistency is used as a stimulus for eliciting missing information and capturing user-defined relationships that arise between elements of an evolving specification.

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