Software Change Through Design Maintenance

Copyright 1997 IEEE. Published in the Proceedings of ICSM’97, September 28 – October 2, 1997 in Bari, Italy. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the IEEE. Contact: Manager, Copyrights and Permissions / IEEE Service Center / 445 Hoes Lane / P.O. Box 1331 / Piscataway, NJ 088-1331, USA. Telephone: + Intl. 908-562-3966. ABSTRACT Conventional software engineering tends to focus on a small part of the software life cycle: the design and implementation of a product. The bulk of the lifetime cost is in the maintenance phase, where one must live with the product previously developed. Presently, we have little theory and fewer tools to help us manage the maintenance activity. We contend that a fundamental cause of the difficulty is the failure to preserve design information. This results from an over preoccupation with the synthesis and maintenance of code. We offer an alternative paradigm: • make the design the central focus of the construction process—get code as a byproduct; • make the design the central focus of the maintenance process—preserve revised designs and get code as a byproduct. A transformational scheme for accomplishing this is presented. We call it the Design Maintenance System. The programming roles change radically from coding instances for ill-defined specifications to specifiers of functionality and (compiler-like) implementation methods. Specification and implementation method debugging would then become prominent activities. The design scheme and change management procedures are illustrated with a simple data processing application. We sketch an ongoing implementation.