View source for FOAF

{{Short description|Semantic Web ontology to describe relations between people}}
{{for|"friend of a friend"|friend of a friend|Friend of a Friend (disambiguation)}}
{{Infobox technology standard
|image=FoafLogo.svg
|image_size=120px
|caption=FOAF logo
|status=Published
|title=FOAF
|native_name=
|series=Namespace Document
|abbreviation=FOAF

|organization=
|authors=Dan Brickley, Libby Miller
|domain=[[Semantic Web]]
|base_standards=[[Resource Description Framework|RDF]], [[Web Ontology Language|OWL]]

|first_published={{Start date and age|2005|06|03}}
|year_started={{Start date and age|2000}}
|version=0.99
|version_date={{Start date and age|2014|1|14}}

|license=[[Creative Commons license|CC BY 1.0]]
|website={{URL|http://xmlns.com/foaf/spec/}}
|long_name=Friend of a friend}}
'''FOAF''' (an acronym of '''[[friend of a friend]]''') is a [[machine-readable data|machine-readable]] [[ontology (information science)|ontology]] describing [[person]]s, their activities and their relations to other people and objects. Anyone can use FOAF to describe themselves. FOAF allows groups of people to describe [[social networks]] without the need for a centralised database.

FOAF is a descriptive vocabulary expressed using the [[Resource Description Framework]] (RDF) and the [[Web Ontology Language]] (OWL). Computers may use these FOAF profiles to find, for example, all people living in Europe, or to list all people both you and a friend of yours know.<ref>[https://web.archive.org/web/20091223003446/http://www.ibm.com/developerworks/xml/library/x-foaf.html XML Watch: Finding friends with XML and RDF] by Edd Dumbill in IBM DeveloperWorks</ref><ref>[https://web.archive.org/web/20100307223814/http://www.ibm.com/developerworks/xml/library/x-foaf2.html XML Watch: Support online communities with FOAF] by Edd Dumbill in IBM DeveloperWorks</ref> This is accomplished by defining relationships between people. Each profile has a unique identifier (such as the person's [[e-mail address]]es, international [[telephone number]], [[Facebook]] account name, a [[Extensible Messaging and Presence Protocol|Jabber ID]], or a [[Uniform Resource Identifier|URI]] of the homepage or weblog of the person), which is used when defining these relationships.

The FOAF project, which defines and extends the vocabulary of a FOAF profile, was started in 2000 by Libby Miller and Dan Brickley. It can be considered the first [[Social Semantic Web]] application,{{citation needed|date=April 2017}} in that it combines [[Resource Description Framework|RDF]] technology with '[[social web]]' concerns.{{clarify|date=April 2017}}

[[Tim Berners-Lee]], in a 2007 essay,<ref>{{cite web |website=Decentralized Information Group |url=http://dig.csail.mit.edu/breadcrumbs/node/215 |title=Giant Global Graph |first=Tim |last=Berners Lee |archive-url=https://web.archive.org/web/20160713021037/http://dig.csail.mit.edu/breadcrumbs/node/215 |archive-date=2016-07-13}}</ref> redefined the [[semantic web]] concept into the [[Giant Global Graph]] (GGG), where relationships transcend networks and documents. He considers the GGG to be on equal ground with the [[Internet]] and the [[World Wide Web]], stating that "I express my network in a FOAF file, and that is a start of the revolution."

==WebID==
FOAF is one of the key components of the [[WebID]] specifications, in particular for the WebID+TLS protocol, which was formerly known as FOAF+SSL.

==Deployment==
Although it is a relatively simple use-case and standard, FOAF has had limited adoption on the web. For example, the [[Live Journal]] and [[DeadJournal]] blogging sites support FOAF profiles for all their members,<ref>{{cite web |website=LiveJournal |title=LiveJournal FOAF |url=http://community.livejournal.com/ljfoaf |archive-url=https://web.archive.org/web/20100118151037/http://community.livejournal.com/ljfoaf |archive-date=2010-01-18}}.</ref> [[My Opera]] community supported FOAF profiles for members as well as groups. FOAF support is present on [[Identi.ca]], [[FriendFeed]], [[WordPress]] and [[TypePad]] services.<ref>{{cite web|url=http://wiki.foaf-project.org/w/DataSources |title=Known FOAF data providers |publisher=FOAF project |url-status=dead |archiveurl=https://web.archive.org/web/20100226072731/http://wiki.foaf-project.org/w/DataSources |archivedate=2010-02-26 }}</ref>

[[Yandex]] blog search platform supports search over FOAF profile information.<ref>{{cite web|date=2008-08-15|title=press release on the social networking support|url=http://company.yandex.com/press_center/press_releases/2008/2008-08-15.xml|publisher=Yandex}}</ref> Prominent client-side FOAF support was available in [[Safari (web browser)|Safari]]<ref>{{cite web | publisher = eJohn | url = http://ejohn.org/blog/foaf-support-in-safari-rss/ | title = FOAF Support in Safari RSS}}.</ref> web browser before RSS support was removed in Safari 6 and in the Semantic Radar<ref>{{cite web | url = https://addons.mozilla.org/en-US/firefox/addon/semantic-radar/ | title = Semantic Radar plugin for the Firefox browser | publisher = Mozilla | access-date = 2012-02-20 | archive-url = https://web.archive.org/web/20140108014347/https://addons.mozilla.org/en-US/firefox/addon/semantic-radar/ | archive-date = 2014-01-08 | url-status = dead }}</ref> plugin for [[Firefox (web browser)|Firefox]] browser. [[Semantic MediaWiki]], the [[semantic annotation]] and [[linked data]] extension of [[MediaWiki]] supports mapping properties to external ontologies, including FOAF which is enabled by default.

There are also modules or plugins to support FOAF profiles or FOAF+SSL authorization for programming languages,<ref>{{cite web | publisher = CPAN | url = https://metacpan.org/pod/XML::FOAF | title = FOAF support module for Perl}}</ref><ref>{{cite web | publisher = CPAN | url = https://metacpan.org/pod/Web::ID | title = FOAF+SSL authentication support for Perl}}</ref> as well as for [[content management systems]].<ref>http://drupal.org/project/foaf - FOAF support for [[Drupal]]</ref>

==Example==
The following FOAF profile (written in [[Turtle (syntax)|Turtle]] format) states that James Wales is the name of the person described here. His e-mail address, homepage and depiction are [[web resource]]s, which means that each can be described using RDF as well. He has Wikimedia as an interest, and knows Angela Beesley (which is the name of a 'Person' resource).

<syntaxhighlight lang="turtle">
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .

<#JW>
    a foaf:Person ;
    foaf:name "James Wales" ;
    foaf:mbox <mailto:jwales@bomis.com> ;
    foaf:homepage <http://www.jameswales.com> ;
    foaf:nick "Jimbo" ;
    foaf:depiction <http://www.jameswales.com/aus_img_small.jpg> ;
    foaf:interest <http://www.wikimedia.org> ;
    foaf:knows [
        a foaf:Person ;
        foaf:name "Angela Beesley"
    ] .

<http://www.wikimedia.org>
    rdfs:label "Wikimedia" .
</syntaxhighlight>

==History==

===Versions===
<!-- Template:Version - for version & release history. Documentation and examples: https://en.wikipedia.org/wiki/Template:Version -->

{| class="wikitable sortable"
|+ Versions table
|-
! Version
! Date
! namespace URI
! Description
|-
| {{Version |o |0.98}}
| {{dts|2010-08-09}}
<!-- Version used by 
     {{section link|Metadata Authority Description Schema|MADS/RDF}}
     unconfirmed, v0.99 and v0.98 both has same xml ns
-->
| http://xmlns.com/foaf/0.1/
|-
| {{Version |c |0.99}}
| {{dts|2014-01-14}}<ref>{{cite web
| last1          = Brickley
| first1         = Dan
| author-link1   = <!-- [[wikidata:Q56641640]] -->
| last2          = Miller
| first2         = Libby
| author-link2   = 
| date           = 2014-01-14
| title          = FOAF Vocabulary Specification 0.99
| work           = xmlns.com
| publisher      = FOAF project
| url            = http://xmlns.com/foaf/spec/20140114.html
| access-date    = 2022-03-31
| archive-url    = https://web.archive.org/web/20220303180551/http://xmlns.com/foaf/spec/20140114.html
| archive-date   = 2022-03-03
| url-status     = live
}}</ref>
| http://xmlns.com/foaf/0.1/
| Current version <!-- not sure if you can call if current "stable" version -->
Paddington Edition
|-
| colspan=4 | {{Version|l|show=010100}}
|}

==See also==
* [[Resource Description Framework]] (RDF)
* [[Web Ontology Language]] (OWL)
* [[Social web]]
* [[Semantic Web]]
* [[wiktionary:DOAC|Description of a Career]] (DOAC)
* [[DOAP|Description of a Project]] (DOAP)
* [[Semantically-Interlinked Online Communities]] (SIOC)
* [[hCard]] (HTML [[vCard]])
* [[XHTML Friends Network]] (XFN)

==References==
{{reflist}}

==External links==
* {{Official website|http://www.foaf-project.org}} ({{Webarchive |url=https://web.archive.org/web/20211023122305/http://www.foaf-project.org/ |date=23 October 2021}})
* [http://ebiquity.umbc.edu/resource/html/id/82/ FOAF dataset] a dataset of 201,612 FOAF triples
* Archived: {{webarchive |url=https://web.archive.org/web/20181130195340/https://www.foaf-search.net/ |date=Nov. 30, 2018 |title= FOAF-search - a search engine for FOAF data }}

{{Semantic Web}}
{{Social networking}}

[[Category:Ontology_(information_science)]]
[[Category:Semantic Web]]
[[Category:2000 software]]