The Process of Inconsistency Management: A Framework for Understanding

The process of managing inconsistency is a fundamental activity that permeates a large part of the systems development process. Failure to identify inconsistencies may lead to major problems in the operation of a system, while failure to support a range of inconsistency handling strategies can lead to a rigid and impractical development process. We argue, therefore, that the inconsistency management process needs to be made explicit, and should play a central role in defining the broader development process. In this paper we sketch out the constituent processes of inconsistency management in the context of an overall requirements engineering process. The framework is based on identification of an explicit set of consistency rules, which capture constraints on the evolving descriptions arising from process, method, notation, domain, etc. The set of consistency rules are refined as the development effort proceeds. The process model distinguishes four major steps: monitoring for inconsistency, diagnosis, handling, and monitoring the outcome. These are supported by the processes of measuring inconsistency, and analyzing the impact and risk associated with different inconsistency handling options. The framework provides a core process model for managing a large set of evolving descriptions during requirements engineering. Because the consistency rules are made explicit, the framework provides greater flexibility for selecting appropriate inconsistency handling actions. It also fully supports the need to adapt the inconsistency management strategy according to local contingencies in the development process.