Modifiability

Definition

Modifiability (a.k.a., Changability, Evolvability, Flexibility)

the development-oriented quality factor representing the degree of the easiness of making changes to a business enterprise, system, application, or component

Classification

As illustrated in the preceding figure, Modifiability is part of the following inheritance hierarchy:

• Type: Abstract
• Superclass: Development-Oriented Quality Factor
• Subclasses:
  • Extensibility:
    • Scalability
  • Maintainability:
    • Adaptive Maintainability
    • Corrective Maintainability
    • Perfective Maintainability
    • Preventative Maintainability

Responsibilities

The typical responsibilities of Modifiability are to:

• Model the degree to which a system, application, or component can be easily changed.
• Support the analysis and specification of modifiability requirements.
• Provide a foundation for evaluating the quality of an architecture.

Subfactors

Modifiability is typically decomposed into the following aggregation hierarchy of subfactors:

• None

Measures

Modifiability is typically measured in terms of:

• The measures used for its subclasses:
  • Extensibility Measures
  • Maintainability Measures

Mechanisms

Typical mechanisms for implementing modifiability include:

• The mechanisms used for its subclasses:
  • Extensibility Mechanisms
  • Maintainability Mechanisms

Guidelines

The following guidelines have been found to be useful regarding modifiability:

• Modifiability includes both:
  • Modifications due to changing requirements (i.e., Extensibility).
  • Modifications not due to changing requirements (i.e., Maintainability).