Reusability

Definition

Reusability

the development-oriented quality factor representing the degree of the easiness of reusing all or part of a work product

Classification

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

• Type: Abstract
• Superclass: Development-Oriented Quality Factor
• Subclasses:
  • System Reusability
  • Application Reusability
  • Component Reusability
  • Document Reusability
  • Requirements Reusability
  • Architecture Reusability
  • Test Reusability
  • Method Component Reusability

Responsibilities

The typical responsibilities of reusability are to:

• Model the degree to which all or part of work products can be reused.
• Support the analysis and specification of reusability requirements.
• Provide a foundation for evaluating the quality of an architecture.

Subfactors

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

• Reuse as is
  (e.g., reuse of a component or subcomponent without modification).
• Reuse with minor modifications
  (e.g., reuse of a component after modifications to its design or implementation).
• Reuse with major modifications
  (e.g., reuse of a component after modifications to its architecture or interfaces).

Measures

Reusability is typically measured in terms of:

• Percent of work products reused
• Number of time the work products reused

Mechanisms

Typical mechanisms for implementing reusability include:

• Reuse repositories.

Guidelines

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

• Reuse Scale.
  Reuse can occur at any scale such as:
  • Reuse of entire “boilerplate” sections of documents down to individual sentences such as textual requirements.
  • Reuse of entire software components through reuse of individual classes or operations.
• Reuse Validation.
  In order to validate requirements specifying potential reusability on future applications, the document or component must meet acceptability criteria (e.g., in terms of quality, documentation, and associated tests) published by the reuse organization. Of course, one does not know if the potentially reusable as documentation and components are in fact reusable until they have actually been reused several times during future endeavors.