Software Maintenance is a very broad activity that takes place once the operation is done. It optimizes the software performance by reducing errors, eliminating useless lines of codes and applying advanced development. It can take up to 1-2 years to build a software system while its maintenance and modification can be an ongoing activity for 15-20 years.
Categories of Software Maintenance:
- Corrective Maintenance
- Adaptive Maintenance
- Perfective Maintenance
- Preventive Maintenance
The cost of system maintenance represents a large proportion of the budget of most organizations that use software system. More than 65% of software lifecycle cost is expended in the maintenance activities.
Cost of software maintenance can be controlled by postponing the. development opportunity of software maintenance but this will cause the following intangible cost:
- Customer dissatisfaction when requests for repair or modification cannot be addressed in a timely manner.
- Reduction in overall software quality as a result of changes that introduce hidden errors in maintained software.
Software maintenance cost factors:
The key factors that distinguish development and maintenance and which lead to higher maintenance cost are divided into two subcategories:
- Non-Technical factors
- Technical factors
The Non-Technical factors include:
- Application Domain
- Staff stability
- Program lifetime
- Dependence on External Enviroment
- Hardware stability
Technical factors include the following:
- module independence
- Programming language
- Programming style
- Program validation and testing
- Configuration management techniques
Efforts expended on maintenance may be divided into productivity activities (for example analysis and evaluation, design and modification, coding). The following expression provides a module of maintenance efforts:
M = P + K(C - D)
M: Total effort expended on the maintenance.
P: Productive effort.
K: An empirical constant.
C: A measure of complexity that can be attributed to a lack of good design and documentation.
D: A measure of the degree of familiarity with the software.