Keeping things consistent

In many applications there is a need to keep shared or related information consistent. For example, in a CADrafting package it is necessary to keep views of an artefact from different perspectives consistent with one another. In software development environments there is a need to keep diagrammatic views, such as OO analysis diagrams, consistent with corresponding textual code. In this paper, we describe a number of techniques we have developed to solve consistency problems in a wide variety of application domains. These techniques include uni- and bi-directional constraints, propagation of discrete change descriptions, and transaction based version merging. 1