FOAF (ontology)

FOAF logo.

"FOAF" redirects here. For the phrase, see friend of a friend.

FOAF (an acronym of Friend of a friend) is a machine-readable ontology describing persons, 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.^[1]^[2] This is accomplished by defining relationships between people. Each profile has a unique identifier (such as the person's e-mail addresses, a Jabber ID, or a 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, in that it combines RDF technology with 'Social Web' concerns.

Tim Berners-Lee, in a 2007 essay,^[3] redefined the Semantic web concept into the Giant Global Graph, 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,^[4] My Opera community supports 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 ^[6] search over FOAF profile information. Prominent client-side FOAF support is available in Safari^[7] web browser, in the Semantic Radar^[8] plugin for Firefox browser, and in the RDF Detective^[9] plugin for the Google Chrome browser.

There are also modules or plugins to support FOAF profiles or FOAF+SSL authorization for programming languages,^[10]^[11] as well as for content management systems.^[12]

Example

The following FOAF profile (written in Turtle format) states that Jimmy 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 "Jimmy Wales" ;
    foaf:mbox <mailto:[email protected]> ;
    foaf:homepage <http://www.jimmywales.com> ;
    foaf:nick "Jimbo" ;
    foaf:depiction <http://www.jimmywales.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" .

References

↑ XML Watch: Finding friends with XML and RDF by Edd Dumbill in IBM DeveloperWorks
↑ XML Watch: Support online communities with FOAF by Edd Dumbill in IBM DeveloperWorks
↑ Berners Lee, Tim. "Giant Global Graph". MA, USA: MIT. |section= ignored (help).
↑ "FOAF". LiveJournal. |section= ignored (help).
↑ "Known FOAF data providers". FOAF project.
↑ "press release on the social networking support". Yandex. 2008-08-15.
↑ "FOAF Support in Safari RSS". eJohn. .
↑ "Semantic Radar plugin for the Firefox browser". Mozilla.
↑ "RDF Detective plugin". Chrome web store. Google.
↑ "FOAF support module for Perl". CPAN.
↑ "FOAF+SSL authentication support for Perl". CPAN.
↑ http://drupal.org/project/foaf - FOAF support for Drupal

External links

Official website
FOAF dataset a dataset of 201,612 FOAF triples
foaf-search.net a search engine for FOAF data

Semantic Web

Background

Sub-topics

Applications

Related topics

Standards

Syntax and supporting technologies	HTTP IRI URI RDF triples RDF/XML JSON-LD Turtle Notation3 N-Triples TriX (no W3C standard) RRID SPARQL XML

Schemas, ontologies and rules	Common logic OWL RDFS Rule Interchange Format Semantic Web Rule Language ALPS

Semantic annotation	eRDF GRDDL Microdata Microformats RDFa SAWSDL Facebook Platform

Common vocabularies	DOAP Dublin Core FOAF hAtom hCalendar hCard hProduct hRecipe hResume hReview SIOC SKOS

Social networks and social media

Types	City Personal Professional Sexual Value

Networks	Distributed social network (list) Enterprise social networking Mobile social network Personal knowledge networking

Services	List of social networking websites List of virtual communities with more than 1 million users List of virtual communities with more than 100 million active users

Concepts and theories	Assortative mixing Interpersonal bridge Organizational network analysis Small-world experiment Social aspects of television Social capital Social data revolution Social exchange theory Social identity theory Social network analysis Social web Structural endogamy

Models and processes	Aggregation Change detection Collaboration graph Collaborative consumption Giant Global Graph Lateral communication Social graph Social network analysis software Social networking potential Social television Structural cohesion

Economics	Collaborative finance Social commerce

Phenomena	Community recognition Complex contagion Consequential strangers Friend of a friend Friendship paradox Six degrees of separation Social invisibility Social network game Social occultation Tribe

Related topics	Researchers User profile Viral messages Virtual community

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