Portability Requirement

Definition

portability requirement

any developer-oriented quality requirement that specifies a required amount of the quality factor portability

Objectives

The typical objectives of a portability requirement are to:

• Ensure that the application or component can be easily and quickly ported to specified new environments if and when necessary.
• Minimize porting costs and schedules.

Examples

The following are typical examples of portability requirements:

• “The average time needed to port the component from Windows 98 to Windows XP shall not exceed two person weeks.”
• “Porting the application from Windows NT to Windows XP shall not require modifying more than 0.5% of the lines of non-comment, non-blank source code.”
• “Porting the application from Windows NT to Windows XP shall not require modifying more than 1.5% of the modules.”
• “The average time needed to port the application from Internet Explorer to Netscape Navigator shall not exceed 6 person weeks.”

Guidelines

The following guidelines have been found to be useful when producing portability requirements:

• The scope of a portability requirement can be:
  • A business enterprise
  • An application
  • A component
  • A center
  • A document
• Because the amount of effort required porting an application or component typically depends on the environment to which it is being ported, portability requirements should specify the potential (probable) environments to which the application or component will be ported.
• When specifying the environments to which the application or component may be ported, the portability requirement should specify the:
  • Hardware platform (i.e., vendor and model).
  • Operating system (i.e., vendor, model, and version such as Microsoft Windows XP).
  • Programming language virtual machines (i.e., vendor, model, and version such as Sun Java Version 2).
  • Browser (i.e., vendor, model, and version such as Microsoft Internet Explorer Version 5.0 and greater).
• Avoid redundancy between portability and interoperability requirements. Clearly decide whether or not virtual machines and browsers are part of the platform.
• Portability requirements are typically specified in terms of the maximum amount of effort permitted for average engineers to port the application or component to the specified environment.
• The implementation of porting requirements typically involves:
  • Updating software components.
  • Updating data and hardware components (e.g., if going porting client software from a workstation to a hand-held wireless device with limited screen space).
  • Updating associated documentation.
  • Quality engineering and testing.
• Porting requirements should not be unnecessarily specified in terms of architectural, design, and implementation constraints and the use of industry best practices that tend to produce portable applications when followed such as:
  • Isolating operating system calls.
  • Minimizing or avoiding the use of machine language.
  • Maximizing the use of portable languages such as Java.
  • Maximizing the use of open interface, distribution, and communications standards (e.g., CORBA, Enterprise Java Beans).
  • Localizing user interface software.
  • Initially targeting common platforms.