Software Quality Through Domain-Driven Certification

Software reuse is being pursued in an attempt to improve programmer productivity. The concept of reuse is to permit various work products of software development to be used on more than one project in order to amortize their development costs. Productivity is not the only advantage of reuse although it is the most widely publicized. By incorporating reusable components into a new product, the components bring with them whatever qualities they possess, and these can contribute to the quality of the new product. This suggests that reuse might be exploited for achieving quality as an entirely separate goal from improving productivity. If useful properties pertaining to quality could be shown to be present in products as a direct result of software development based on reuse, this might be a costeffective way of achieving those qualities irrespective of the productivity advantages. The adjective certified is sometimes used to describe components that have been tested in some way prior to entry into a library but the term certified is not formally defined in the reuse literature. In this paper, we address the issue of certifying reusable components. We advocate the development of software by reuse with the specific intent of establishing as many of the required properties in the final product as possible by depending upon properties present in the reusable components. For this goal to succeed, a precise definition of certification of reusable components is required and such a definition is presented. The benefits of the definition and the way in which it supports the goal are explored.