FOAF (friend of a friend) is a machine-readable ontology that describes persons, their activities, and social connections without a central database, enabling the creation of decentralized social networks. Expressed using the Resource Description Framework and the Web Ontology Language, FOAF profiles use unique identifiers like e-mail addresses or URIs to define relationships. Initiated in 2000 by Libby Miller and Dan Brickley, FOAF is considered a pioneer of the Social Semantic Web. Tim Berners-Lee later expanded this idea into the Giant Global Graph, envisioning FOAF as a revolutionary step in the evolution of the semantic web.
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,4 My Opera community supported FOAF profiles for members as well as groups. FOAF support is present on Identi.ca, FriendFeed, WordPress and TypePad services.5
Yandex blog search platform supports search over FOAF profile information.6 Prominent client-side FOAF support was available in Safari7 web browser before RSS support was removed in Safari 6 and in the Semantic Radar8 plugin for 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,910 as well as for content management systems.11
Example
The following FOAF profile (written in Turtle format) states that James Wales is the name of the person described here. His e-mail address, homepage and depiction are web resources, 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).
@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:[email protected]> ; 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" .History
Versions
Versions table| Version | Date | namespace URI | Description |
|---|---|---|---|
| Unsupported: 0.98 | August 9, 2010 | http://xmlns.com/foaf/0.1/ | |
| Latest version: 0.99 | January 14, 201412 | http://xmlns.com/foaf/0.1/ | Current version Paddington Edition |
| Legend:UnsupportedSupportedLatest versionPreview versionFuture version | |||
See also
- Resource Description Framework (RDF)
- Web Ontology Language (OWL)
- Social web
- Semantic Web
- Description of a Career (DOAC)
- Description of a Project (DOAP)
- Semantically-Interlinked Online Communities (SIOC)
- hCard (HTML vCard)
- XHTML Friends Network (XFN)
External links
- Official website (Archived 23 October 2021 at the Wayback Machine)
- FOAF dataset a dataset of 201,612 FOAF triples
- Archived: FOAF-search - a search engine for FOAF data at the Wayback Machine (archived 2018-11-30)
References
XML Watch: Finding friends with XML and RDF by Edd Dumbill in IBM DeveloperWorks https://web.archive.org/web/20091223003446/http://www.ibm.com/developerworks/xml/library/x-foaf.html ↩
XML Watch: Support online communities with FOAF by Edd Dumbill in IBM DeveloperWorks https://web.archive.org/web/20100307223814/http://www.ibm.com/developerworks/xml/library/x-foaf2.html ↩
Berners Lee, Tim. "Giant Global Graph". Decentralized Information Group. Archived from the original on 2016-07-13. https://web.archive.org/web/20160713021037/http://dig.csail.mit.edu/breadcrumbs/node/215 ↩
"LiveJournal FOAF". LiveJournal. Archived from the original on 2010-01-18.. https://web.archive.org/web/20100118151037/http://community.livejournal.com/ljfoaf ↩
"Known FOAF data providers". FOAF project. Archived from the original on 2010-02-26. https://web.archive.org/web/20100226072731/http://wiki.foaf-project.org/w/DataSources ↩
"press release on the social networking support". Yandex. 2008-08-15. http://company.yandex.com/press_center/press_releases/2008/2008-08-15.xml ↩
"FOAF Support in Safari RSS". eJohn.. http://ejohn.org/blog/foaf-support-in-safari-rss/ ↩
"Semantic Radar plugin for the Firefox browser". Mozilla. Archived from the original on 2014-01-08. Retrieved 2012-02-20. https://web.archive.org/web/20140108014347/https://addons.mozilla.org/en-US/firefox/addon/semantic-radar/ ↩
"FOAF support module for Perl". CPAN. https://metacpan.org/pod/XML::FOAF ↩
"FOAF+SSL authentication support for Perl". CPAN. https://metacpan.org/pod/Web::ID ↩
http://drupal.org/project/foaf - FOAF support for Drupal https://drupal.org/project/foaf ↩
Brickley, Dan; Miller, Libby (2014-01-14). "FOAF Vocabulary Specification 0.99". xmlns.com. FOAF project. Archived from the original on 2022-03-03. Retrieved 2022-03-31. http://xmlns.com/foaf/spec/20140114.html ↩