Maintenance involves making changes to software after it has been delivered to the client. There are three categories of maintenance: corrective, adaptive, and perfective. Corrective maintenance fixes bugs, adaptive maintenance makes changes due to environment changes like new hardware or software, and perfective maintenance adds new features or functionality. Factors like insufficient documentation, too many versions, staff mobility, and external changes can negatively impact maintenance. Maintenance is a significant cost, estimated to be between 40-70% of total software development costs.

1. Maintenance

2. Making changes to the software after it has been
handed over to the client, and enters productive use.
Maintenance

3. Maintenance activities
There are 3 categories of maintenance:
Corrective maintenance
Adaptive maintenance
Perfective maintenance

4. Fixing bugs and removing errors which did not show
up in the software development and testing phases.
Corrective maintenance

5. Changes to the environment in which the software
operates means necessary changes to the code
Could be updated operating system, or new hardware
Adaptive maintenance

6. Responding to user requests for changes in
functionality or additional features
Perfective maintenance

7. Maintenance activities

8. New applications
As users gain experience of a new application, they
will begin to see potential improvements and
features.
Staff mobility
It is always easier for the original programmer to
update the code than someone else. When staff
move on, it becomes harder to maintain code unless
it is very well documented.
Factors affecting maintenance

9. Too many versions
It can be difficult to trace changes in code if there
have been a number of releases.
Use of version control can help this problem
Factors affecting maintenance

10. Insufficient documentation
If the design documentation or internal commentary
is poor or missing, then maintenance will be
affected.
Factors affecting maintenance

11. Insufficient documentation
A good use of variable names and internal commentary:
Factors affecting maintenance

12. External hardware and software changes
Changes to hardware platforms, or upgrades to
operating systems can affect maintenance
requirements.
Factors affecting maintenance

13. The cost of maintenance will obviously vary from one
project to another.
It is estimated that between 40% and 70% of the
overall software development lifecycle costs are
spent on maintenance.
The cost of maintenance