SOFTWARE REUSE

Lesson I

A. Introduction to Software Reuse

What is Software reuse? Integration and use of software assets from a previously developed system.

Types of Software Reuse:

Reuse over fungible systems

• portability
• commonality
• ex: numeric types of fixed range and/or precision

Reuse over different domains

• inheritance and binding
• generality and instantiation
• ex: object oriented programming, generics, templates, unconstrained types

Reuse over time

• maintenance
• evolution
• versions
• ex:product lines to be updated over time (such as the 360 family), updating programs for the year 2000

• Code
• Requirements
• Architecture/design documents
• Test Plans
• Manuals
• Templates for any asset
• Design decisions

• Cost
• Time
• Reliability
• Existing parts have experience and real data that testing does not provide
• note: it takes MORE time to design for reuse (producer)

• it takes less time to design with reuse (consumer)

• Generation requires mature domain
• Composition requires mature library system

Role of Domain Analysis
• Context analysis
• Domain modeling
• Domain architectures
  • object oriented
  • event driven
  • functional decomposition

Role of Reuse Libraries

• defining the interface/ specification
• defining the implementation
• object oriented programming/ inheritance
• generics/ templates
• module decomposition/ parameter passing
• user defined types / strong typing
• portability features
• generality

Reference : Software Reuse Executive Primer, May 17, 1995

C. Ada 83/95

History - goals of Ada83, Ada95

DoD needs
• single language - portability, training
• efficiency
  • embedded systems
• reliability
  • software engineering
  • encapsulation
• maintenance
  • evolution
• reusability
  • user defined types
  • features for modularity
  • generics
  • object oriented features of Ada95
• megaprogramming
  • separate compilation
  • package specification
  • interface definition

Reference: Wegner, P. Capital-intensive software technology. IEEE Software 1,3 (July 1984) 7-45

Assignment: pick a topic on reuse for a class report