Forward compatibility

From Wikipedia, the free encyclopedia
  (Redirected from Forward compatible)
Jump to: navigation, search

Forward compatibility or upward compatibility is a design characteristic that allows a system to accept input intended for a later version of itself. The concept can be applied to entire systems, electrical interfaces, telecommunication signals, data communication protocols, file formats, and computer programming languages. A standard supports forward compatibility if a product that complies with earlier versions can "gracefully" process input designed for later versions of the standard.

The objective for forward compatible technology is for old devices to recognise when data has been generated for new devices.[1]

Forward compatibility for the older system implies backward compatibility for the new system, i.e. the ability to process data from the old system; the new system effectively has full compatibility with the older one, by being able to both process and generate data in the format of the older system.

Forward compatibility is not the same as extensibility. A forward compatible design can process at least some of the data from a future version of itself. An extensible design makes upgrading easy. An example of both design ideas can be found in web browsers. At any point in time, a current browser is forward compatible if it gracefully accepts a newer version of HTML. Whereas how easily the browser code can be upgraded to process the newer HTML determines how extensible it is.

Examples[edit]

Telecommunication standards[edit]

The introduction of FM stereo transmission, or color television, allowed forward compatibility, since monophonic FM radio receivers and black-and-white TV sets still could receive a signal from a new transmitter.[1] It also allowed backward compatibility since new receivers could receive monophonic or black-and-white signals generated by old transmitters.[citation needed]

Video gaming[edit]

HTML[edit]

HTML is designed to treat all tags in the same way (as inert, unstyled inline elements) unless their appearance or behavior is overridden; either by the browser's default settings, or by scripts or styles included in the page.[3] This makes most new features degrade gracefully in older browsers. One case where this did not work as intended was script and style blocks, whose content is meant to be interpreted by the browser instead of being part of the page. Such cases were dealt with by enclosing the content within comment blocks.[4]

NUC (not upwardly compatible)[edit]

Some products are not designed to be forward compatible, which has been referred to as NUC (not upwardly compatible). In some cases this might be intentional by the designers as a form of vendor lock-in or software regression.

For example, a cubicle producer considers changing their cubicle design. One designer promotes changing the footprint from 4 foot square to 1.2 meter square. Immediately, the sales manager calls "NUC" and the problem is understood: if the footprint changes and existing customers are considering buying more from the producer, they will have to fit a different sized unit in an office designed for the 4 foot square cubicle.

Planned obsolescence is a type of upward compatibility, but rather than adopting a policy of backwards compatibility, companies adopt a commercial policy of backwards incompatibility so that newer apps require newer devices.

See also[edit]

References[edit]

  1. ^ a b Tulach, Jaroslav (2008). Practical API Design: Confessions of a Java Framework Architect. Apress. p. 233. ISBN 978-1-4302-0973-7. 
  2. ^ Game Boy - Compatibility Chart. Nintendo of America. Retrieved 3 October 2017.
  3. ^ Really undoing html.css by Eric A. Meyer.
  4. ^ HTML <!--...--> Tag at w3schools.com: 'You can also use the comment tag to "hide" scripts from browsers without support for scripts [...]'.

This article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later.

External links[edit]