Software Evolution and Maintenance

4 REENGINEERING

Neither situation nor people can be altered by the interference of an outsider. If they are to be altered, that alteration must come from within.

—Phyllis Bottome

4.1 GENERAL IDEA

Reengineering is the examination, analysis, and restructuring of an existing software system to reconstitute it in a new form and the subsequent implementation of the new form. The goal of reengineering is to:

• understand the existing software system artifacts, namely, specification, design, implementation, and documentation; and
• improve the functionality and quality attributes of the system. Some examples of quality attributes are evolvability, performance, and reusability.

Fundamentally, a new system is generated from an operational system, such that the target system possesses better quality factors. The desired software quality factors include reliability, correctness, integrity, efficiency, maintainability, usability, flexibility, testability, interoperability, reusability, and portability [1]. In other words, reengineering is done to convert an existing “bad” system into a “good” system [2]. Of course there are risks involved in this transformation, and the primary risks are: (i) the target system may not have the same functionality as the existing system; (ii) the target system may be of lower quality than the original system; and (iii) the benefits are not realized in the required time frame [3]. Software systems are reengineered by keeping one or more of the following ...