This document discusses software maintenance. It defines maintenance as modifying software after delivery to fix bugs, improve performance, or adapt to changes. Approximately 70% of software costs are for maintenance. Maintainability refers to how easy software is to correct, adapt, or enhance. Common maintenance types are corrective, adaptive, and perfective. Proper documentation and design are important to reduce maintenance costs and issues like degraded structure over time.

1. Software Maintenance
Indu Sharma
HOD(CSE)
CPTC, Rajsamand

2. Introduction
 One of the important objectives of the
development process should be to produce
software that is easy to maintain.
 After the software has been installed, now
maintenance phase starts. The
maintenance of the software represents up to
70% total life cycle cost of software.

3. What is Maintainability?
 It is one of the measures of software
quality. Maintainability is the ease with
which a program can be corrected if an
error is encountered, adapted if its
environment changes, or enhanced if
the customer desires a change in
requirements.

4. Why Software Change?
 It is impossible to produce systems of any
size which do not need to be changed. Once
software is put into use, new requirements
emerge and existing requirements change as
the business running that software changes.
Parts of the software may have to be modified
to correct error that are found in operation,
improve its performance. All of these means
that, after delivery, software systems always
evolve in response to demands for change.

5. Maintenance Definition
 The Process of changing a system after
it has been delivered and is in use is
called software maintenance.
 According to IEEE:
 Software maintenance is 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.

6. Types of Maintenance
 There are three different types of
software changes (or maintenance
activities):
 Correction(or Corrective
Maintenance): Even with the best
quality activity, it is likely that the
customer will uncover defects in the
software. Corrective maintenance
changes the software to correct defects.

7. Types of Maintenance
 Adaption (Or Adaptive Maintenance)
: Over time the original environment (eg
CPU, O/S, Business rules, government
policies etc. ) for which the software was
developed is likely to change. Adaptive
maintenance results in modification to
software to accommodate changes to its
external environment.

8.  Enhancement(Or Perfective
Maintenance) : As software is used, the
customer/user will recognize additional
functions that will provide benefits.
Perfective maintenance extends the
software beyond its original functional
requirements.
Perfective maintenance refers to
enhancements: making the product better,
faster, smaller, better documented, cleaner
structured, with more functions or reports.
Types of Maintenance

9. Problems: Maintenance
The costs of adding functionality to a system
after it has been put into operation are usually
much greater than providing similar
functionality when software is originally
developed. The reasons for this:
(I) Maintenance staff are often relatively
inexperienced and unfamiliar with application
domain. It is seen as a less skilled process
than system development and is often
allocated to the most junior staff.

10. (II) The programs being maintained may have
been developed many years ago without modern
software engineering techniques. They may be
unstructured and optimized for efficiency rather
than understandability
(III) Changes made to a program may introduce
new faults which trigger further change requests.
New faults may be introduced because the
complexity of the system may make it difficult to
assess the effects of a change.
Problems: Maintenance

11. (IV) As a system is changed, its structure tends to
degrade. This makes the system harder to
understand and makes further changes difficult as the
program becomes less cohesive.
(V) The links between a program and its associated
documentation are sometimes lost during the
maintenance process. The documentation may
therefore be an unreliable aid to program
understanding.
Problems: Maintenance

12. Solutions: Maintenance
 The first of these problems can only be
tackled by organizations adopting enlightened
maintenance management policies.
Management must demonstrate to engineers
that maintenance is of equal value and is as
challenging as original software development.
The best designers and programmers should
be challenged and motivated by system
maintenance.

13. The second of the above problems, can be tackled
using re-engineering and design recovery techniques.
The third and fourth problems are process
problems. Structure naturally degrades with change.
For this organizations must plan to invest extra effort
and resources with the aim of maintaining the structure.
Good software engineering practice such as use of
information hiding or object-oriented development helps
minimize the structure degradation. These techniques
also reduce the probability of faults introduction when
change are made.
Solutions: Maintenance

14. The loss of traceability from code to design
documents may be a consequence of poor
configuration management.
Properly produced and maintained system
documentation is a tremendous aid to maintenance
engineers. The system documentation includes all of
the documents describing the implementation of the
system from the requirements specification to the
final acceptance test plan.
Solutions: Maintenance

15. The Maintenance Process
Change
Requests
Impact
Analysis
System
release
planning
Change
implement
ation
System
release
Perfective
maintenance
Adaptive
maintenance
Corrective
maintenance

16. The Maintenance Process
 Change Requests: This process is
triggered by a set of change requests from
system users, management, or customers.
 Impact Analysis: The cost and impact of
these changes are assessed.
 System release planning: If the proposed
changes are accepted, a new release of the
system is planned. This release will usually
involve elements of adaptive, corrective, and
perfective maintenance.

17.  Change Implementation: The
changes are implemented and validated
 System release: A new version of the
system is released.
The process then iterates with a new
set of changes proposed for the new
release.
The Maintenance Process

18. Emergency Repair Approach
Change
Requests
Analyse
source
code
Modify
source
code
Delivered
repaired
system
Change requests sometimes relate to
system problems that must be tackled
urgently.
The danger with this approach is that
design documents are not updated.