Software Maintenance -

The term maintenance, when accompanied to software, assumes a meaning profoundly different from the meaning it assumes in any other engineering discipline. In fact, many engineering disciplines intend maintenance as the process of keeping something in working order, in repair. The key concept is the deterioration of an engineering artifact due to the use and the passing of time; the aim of maintenance is therefore to keep the artifact’s functionality in line with that defined and registered at the time of release.

Software systems now invade every area of daily living. Yet, we still struggle to build systems we can really rely on. If we want to work with software systems at any level, we need to get to grips with the way software evolves. This book will equip the reader with a sound understanding of maintenance and how it affects all levels of the software evolution process.

In software engineering, software maintenance is the process of enhancing and optimizing deployed software (software release), as well as remedying defects. Software maintenance is one of the phases in the software development process, and follows deployment of the software into the field. The software maintenance phase involves changes to the software in order to correct defects and deficiencies found during field usage as well as the addition of new functionality to improve the software's usability and applicability.

Software maintenance involves a number of specific techniques. One technique is static slicing, which is used to identify all the program code that can modify some variable. It is generally useful in refactoring program code and was specifically useful in assuring Y2K compliance. The software maintenance phase is an explicit part of the waterfall model of the software development process which was developed during the structured programming movement of computer programming. The other major model, the spiral model developed during the object oriented movement of software engineering makes no explicit mention of a maintenance phase. Nevertheless, this activity is notable, considering the fact that two-thirds of a software system's lifetime cost involves maintenance.