1. Contents Introduction Requirements Engineering Project Management
Software Design
Detailed Design and Coding
Quality Assurance
Software Maintenance
Analysis
Design
Testing
Coding
Operation and
Maintenance
Installation
Require-
ments
Requirements
Specification
Planning
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2. Software Maintenance Process
The most expensive part of the software lifecycle!
Require-
ments
Change Request
Impact Analysis
Release Planning
Change Design
Implementation
Test
Release Change
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3. Ian Sommerville 1995  Software Engineering, 5th edition.

4. Impact Analysis An Impact Analysis
identifies all systems/system products affected by a change request developing an estimate of the resources needed to accomplish the change
Steps:
Evaluate Change Requests
Estimate Resources
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5. Types of Maintenance Corrective Adaptive Perfective Preventive
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6. Corrective Maintenance
Focuses on fixing defects
Is a reactive process
I.E. Defects generally need to be corrected either immediately or in the near future
Defects
Refer to the system not performing as originally intended or as specified in the requirements
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7. Adaptive Maintenance
Includes all work related to how the software functions
I.E. Relates to enhancing software functionality
Includes all changes to meet the evolving needs of the user and the environment
I.E. System changes, additions, insertions, deletions, modifications, extensions and enhancements
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8. Perfective Maintenance
Includes all efforts to improve the quality of the software
Includes restructuring code, creating and updating documentation, improving reliability or efficiency
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9. Preventive Maintenance
Preventing system performance from degrading to unacceptable levels
“Occurs when software is changed to improve future supportability or reliability, or to provide the basis for future enhancements.”
Maintenance work in the above categories is often performed concurrently
Pressman, 1992
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10. Use of Maintenance Time
*See [Schach 97].
**See [Somm 96].
***See [Pfleeger 98].
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11. Maintenance Metrics Control complexity Data complexity
Length of identifier names
Program comments
Coupling
Cohesion
Degree of user interaction
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12. Software Maintenance Summary
There are 4 categories of maintenance
corrective, adaptive, perfective, preventative
There is a defined maintenance process, which ensures the delivery of quality software
A procedure with 7 steps.
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13. Configuration Management
New versions of software systems are created as they change
For different machines/OS
Offering different functionality
Tailored for particular user requirements
Configuration management is concerned with managing evolving software systems
System change is a team activity
CM aims to control the costs and effort involved in making changes to a system
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14. Version and release management
Invent identification scheme for system versions
Plan when new system version is to be produced
Ensure that version management procedures and tools are properly applied
Plan and distribute new system releases
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15. Storing Versions Naive: Separate files for each version
Version handling by numbering schemes
Double Maintenance Problem
Solution: One original version plus deltas
Forward deltas
Backward deltas
Forward and backward deltas
Shared Data Problem
Simultaneous Update Problem
Solution: Check-in/check-out mechanism
Still a problem: Merging versions
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16. Tools for Version and Configuration Control
General:
History- and log-files
Hierarchical file systems
...
Version Control:
Modification tracking
Control of development branches
Efficient storage and retrieval
Access control
Merging versions
SCCS, RCS, CVS, ...
File comparators
Patch generators
Configuration control:
Dependency management and control
System creation
Integration with version control
...
Make, makefile generators, ...
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17. Software Rejuvenation
Redocumentation: static analysis adds more information
Restructuring: transform to improve code structure
Reverse engineering: recreate design and specification information from the code
Reengineering: reverse engineer and then make changes to specification and design to complete the logical model; then generate new system from revised specification and design
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