2.6 Software maintenance  (Page 2/10)

Definitions and terminology

Software maintenance is defined as the modification of a software product after delivery to correct faults, to improve performance or other attributes, or to adapt the product to a modified environment. The standard also addresses maintenance activities prior to delivery of the software product, but only in an information appendix of the standard.

The IEEE/EIA 12207 standard for software life cycle processes essentially depicts maintenance as one of the primary life cycle processes, and describes maintenance as the process of a software product undergoing “modification to code and associated documentation due to a problem or the need for improvement. The objective is to modify the existing software product while preserving its integrity”.

Nature of maintenance

Software maintenance sustains the software product throughout its operational life cycle. Modification requests are logged and tracked, the impact of proposed changes is determined, code and other software artifacts are modified, testing is conducted, and a new version of the software product is released. Also, training and daily support are provided to users. Pfleeger states that “maintenance has a broader scope, with more to track and control” than development.

A maintainer is defined by IEEE/EIA 12207 as an organization which performs maintenance activities, sometimes refer to individuals who perform those activities, contrasting them with the developers.

IEEE/EIA 12207 identifies the primary activities of software maintenance as: process implementation; problem and modification analysis; modification implementation; maintenance review/acceptance; migration; and retirement.

Maintainers can learn from the developer’s knowledge of the software. Contact with the developers and early involvement by the maintainer helps reduce the maintenance effort. In some instances, the software engineer cannot be reached or has moved on to other tasks, which creates an additional challenge for the maintainers. Maintenance must take the products of the development, code, or documentation, for example, and support them immediately and evolve/maintain them progressively over the software life cycle.

Need for maintenance

Maintenance is needed to ensure that the software continues to satisfy user requirements. Maintenance is applicable to software developed using any software life cycle model (for example, spiral). The system changes due to corrective and non-corrective software actions. Maintenance must be performed in order to:

• Correct faults
• Improve the design
• Implement enhancements
• Interface with other systems
• Adapt programs so that different hardware, software, system features, and telecommunications facilities can be used
• Migrate legacy software
• Retire software

The maintainer’s activities comprise four key characteristics, according to Pfleeger:

• Maintaining control over the software’s day-to-day functions
• Maintaining control over software modification
• Perfecting existing functions
• Preventing software performance from degrading to unacceptable levels