Nested Context Language: Difference between revisions

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{{short description|Declarative authoring language for hypermedia documents}}

{{Technical|date=September 2009}}

In the field of digital and interactive television, '''Nested Context Language''' (NCL)''' is a [[Declarative programming|declarative authoring language]] for [[hypermedia]] documents. NCL documents do not contain multimedia elements such as audio or video content; rather they function as a "glue" language that specifies how multimedia components are related. In particular, NCL documents specify how these components are synchronized relative to each other and how the components are composed together into a unified document. Among its main facilities, it treats hypermedia relations as first-class entities through the definition of hypermedia connectors, and it can specify arbitrary semantics for a hypermedia composition using the concept of composite templates.

NCL is an [[XML]] application language that is an extension of [[XHTML]], with XML elements and attributes specified by a modular approach. NCL modules can be added to standard web languages, such as [[XLink]] and [[Synchronized Multimedia Integration Language|SMIL]].

NCL was initially designed for the Web environment, but a major application of NCL is use as the declarative language of theJapanesethe Japanese-Brazilian [[ISDB-Tb]] (International Standard for Digital Broadcasting) terrestrial DTV [[digital television]] [[middleware]] (named [[Ginga (SBTVD Middleware)|Ginga]]). It is also the first standardized technology of the [[ITU-T]] multimedia application framework series of specifications for [[IPTV]] (internet protocol television) services. In both cases it is used to develop interactive applications to digital television.

==Structure of an NCL document==

NCL was designed to be modular to allow for use of subsets of modules according to the needs of the particular application. The 3.1 version of the standard is split into 14 areas with each module assigned to an area.<ref>{{cite web|title=H.761 “Nested"Nested context language (NCL) and Ginga-NCL”NCL" (Rev.): Initial draft of revised text|url=http://profesores.elo.utfsm.cl/~agv/elo323/GINGA/ITU-H761.pdf|publisher=INTERNATIONAL TELECOMMUNICATION UNION|accessdate=18 February 2014}}</ref> Each module in turn defines one or more [[XML#Key terminology|XML elements]]. The areas and associated modules are

*Structure

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**Metainformation Module

==NCL Profilesprofiles==

Profiles are standard subsets of modules. Profiles defined by the standard include

* '''Full Profileprofile''' -– includes all NCL Modules

* '''Enhanced Digital TV profile (EDTV)''' - – includes the Structure, Layout, Media, Context, MediaContentAnchor, CompositeNodeInterface, PropertyAnchor, SwitchInterface, Descriptor, Linking, CausalConnectorFunctionality, ConnectorBase, TestRule, TestRuleUse, ContentControl, DescriptorControl, Timing, Import, EntityReuse, ExtendedEntityReuse, KeyNavigation, Animation, TransitionBase, Transition and Metainformation modules

* '''NCL Basic Digital TV profile (BDTV)''' -– includes the Enhanced Digital TV profiles except for the Animation, TransitionBase and Transition modules

==Authoring Toolstools==

Tools for creating interactive DTV application in NCL include:

* [[NCL Eclipse]]

Tools for creating interactive DTV application in NCL include [[NCL Eclipse]] and* NCL Composer.<ref>{{cite web|title=Welcome to NCL Composer website|url=http://composer.telemidia.puc-rio.br/en/start|publisher=PUC-Rio|accessdate=19 February 2014}}</ref>

==See also==

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==Further reading==

*{{cite book|author=Marcelo S. Alencar|title=Digital Television Systems|url=httphttps://books.google.com/books?id=M96rKRAqHFgC&pg=PA198|date=19 March 2009|publisher=Cambridge University Press|isbn=978-0-521-89602-3|page=198}}

*{{cite book|author=Shūji Hashimoto|title=Multimedia Modeling: Modeling Multimedia Information and Systems : Nagano, Japan, November 13-15, 2000|url=httphttps://books.google.com/books?id=xqOUeONT6qYC&pg=PA72|date=1 January 2000|publisher=World Scientific|isbn=978-981-02-4489-7|pages=72, 79,86-87 86–87}}

*{{cite journal|journal=Journal of the Brazilian Computer Society|date=November 2010|volume=16|issue=4|pages=229-245229–245|title=The Nested Context Language reuse features|author1=Carlos de Salles Soares Neto|author2=Luiz Fernando Gomes Soares|author3=Clarisse Sieckenius de Souza|urldoi=http://link.springer.com/article/10.1007/s13173-010-0017-z}}{{paywall|doi-access=free}}

*{{cite book|author=Jean-Yves Vion-Dury|title=Proceedings of the ACM Symposium on Document Engineering|url=httphttps://books.google.com/books?id=SEpPAAAAMAAJ|year=2004|publisher=ACM Press|page=188ff|isbn=9781581139389}}

==External links==

* [http://www.ncl.org.br NCL Official Web Site]

* [http://handbook.ncl.org.br/ NCL Handbook]

* [http://www.telemidia.puc-rio.br Telemidia LabsLab]

* [http://www.telemidia.puc-rio.br/~roberto/ncl-resources NCL Resources]: a number of resources supporting NCL.

===NCL Playersplayers===

* [http://softwarepublicoginga.govorg.br/ver-comunidade?community_id=1101545 GINGA-NCL Reference Implementation], available under GPLv2 (in Portuguese).

* [httphttps://ghtvgithub.com.br/expertisesolutions/ghtv-ncl-player GHTV GINGA-NCL player] for Windows and Linux under [[Creative Commons licenses|Creative Commons]] Attribution-NonCommercial-NoDerivs 3.0 License (in Portuguese).

* [https://github.com/lince/webncl WebNCL Player] Web-based, available under GPL.

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[[Category:Broadcast engineering]]

[[Category:Digital television]]

[[Category:ISDB]]