Hypertext Application Language: Difference between revisions

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{{Short description|Proposed computer definition standard}}

'''Hypertext Application Language''' ('''HAL''') is an [[Internet Draft]] (a "work in progress") standard convention for defining [[hypermedia]] such as links to external [[web resource|resources]] within [[JSON]] or [[XML]] code. It is documented in an [[Internet Draft]] (a "work in progress"), with the latest version 11 published the 10th of October 2023. The standard was initially proposed onin June 2012, specifically for use with JSON,<ref>{{cite web |last1=Kelly |first1=Mike |title=JSON Hypertext Application LanuageLanguage |url=https://tools.ietf.org/html/draft-kelly-json-hal-00 |publisher=IETF |accessdate=16 October 2018 |date=7 June 2012}}</ref> and has since become available in two variations, one each for JSON and XML. The two associated [[MIME]] types are media type: application/hal+xml and media type: application/hal+json.<ref>{{cite book|last1=Richardson|first1=Leonard|last2=Ruby|first2=Mike Amundsen ; foreword by Sam|title=RESTful Web APIs|date=2013|publisher=O'Reilly|___location=Sebastopol, CA|isbn=978-1-4493-5806-8|edition=First|chapter=7}}</ref>

HAL was created to be simple to use and easily applicable across different [[___domain (software engineering)|domains]] by avoiding the need to impose any requirements on how the project be structured. Maintaining this minimal impact approach, HAL has enabled developers to create general-purpose [[library (computing)|libraries]] which can be easily incorporated on any [[API]] that uses HAL.{{Citation needed|Reasonreason=RFC4627 does not mention HAL|date=16 October 2018}}

APIs that adopt HAL simplify the use of [[open-source software|open source]] libraries and make it possible to interact with the [[application programming interface|API]] using JSON or XML. The alternative would be having to develop a [[proprietary format]] which in turn forces developers to learn how to use yet another foreign format.<ref name="stateless">{{cite web|last1=Kelly|first1=Mike|title=HAL - Hypertext Application Language A lean hypermedia type|url=httphttps://stateless.cogroup/hal_specification.html|accessdate=23 July 2014|date=2011-06-13}}</ref>

== Convention ==

HAL is structured in such a way as to represent elements based on two concepts: Resources and Links. Resources consist of [[URI]] links, embedded resources, your standard data (be it JSON or XML), and non URI links. Links have a target URI, as well as the name of the link (referred to as 'rel'), as well as optional properties designed to be mindful of deprecation and content negotiation.<ref name="stateless"/>

==Example==

General Resource

<sourcesyntaxhighlight lang="json">

{

"_links": {

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"name": "HAL Cookbook"

}

</syntaxhighlight>

</source>

Embedded resource

<sourcesyntaxhighlight lang="json">

{

"_links": {

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"_links": {

"self": {

"href": "http://author-example.com/api/author/shahadat"

}

},

"id": "shahadat",

"name": "Shahadat Hossain Khan",

"homepage": "http://author-example.com"

}

},

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"name": "HAL Cookbook"

}

</syntaxhighlight>

</source>

Collections

<sourcesyntaxhighlight lang="json">

{

"_links": {

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"_links": {

"self": {

"href": "http://author-example.com/api/author/shahadat"

}

},

"id": "shahadat",

"name": "Shahadat Hossain Khan",

"homepage": "http://author-example.com"

}

},

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"name": "HAL Cookbook"

}

</syntaxhighlight>

</source>

==See also==

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==External links==

* [https://tools.ietf.org/html/draft-kelly-json-hal-0811 JSON Hypertext Application Language latest draft]

[[Category:JSON]]

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[[Category:XML-based standards]]

[[Category:World Wide Web Consortium standards]]

{{Web-stub}}