9: Software maintenance

What is software maintenance?

Modifying a program after we attend to put it to use

Types of software maintenance

• Fault repairs

  • Bug fixes

• Environmental adaptation

  • Software to adapt to a new environment

• Functionality addition and modification

  • Adding functionality to satisfy new requirements

Maintenance cost vs environmental cost

Maintenance cost is usually more expensive to add new features than during development

Maintenance prediction

Concerns assessment of the parts of the system that may cause problems

Change Prediction

Predicting the number of changes being requested

Complexity matrix

Predictions of the maintainability can be made by assessing the complexity of system components

Process matrix

May be used to estimate maintainability

Software Reengineering

• Rewrite the part of legacy system without changing functionality

• Reduce the risk and reduce the cost (mainly reduce the risk)

Refactoring

• Improve structure, reduce functionality

• NO ADDING FUNCTIONALITY

• Done throughout the evolution process

“Bad smells” in software

• Duplicate code

• Long methods

• Switch statements