FOAF (software)

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FOAF logo.

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 him or herself. FOAF allows groups of people to describe social networks without the need for a centralised database.

FOAF is a descriptive vocabulary expressed using RDF Resource Description Framework and OWL Web Ontology Language. 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. 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[1] redefined the Semantic web concept into something he calls the Giant Global Graph, where relationships transcend networks/documents. He considers the GGG to be on equal grounds with Internet and World Wide Web, stating that "I express my network in a FOAF file, and that is a start of the revolution."

[edit] Example

The following FOAF profile (written in XML format) states that Jimmy Wales is the name of the person described here. His e-mail address, homepage and depiction are resources, which means that each of them can be described using RDF as well. He has Wikipedia as an interest, and knows Angela Beesley (which is the name of a 'Person' resource).

<rdf:RDF xmlns:foaf="http://xmlns.com/foaf/0.1/" 
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#">
    <foaf:Person rdf:about="#JW">
        <foaf:name>Jimmy Wales</foaf:name>
        <foaf:mbox rdf:resource="mailto:jwales@bomis.com" />
        <foaf:homepage rdf:resource="http://www.jimmywales.com/" />
        <foaf:nick>Jimbo</foaf:nick>
        <foaf:depiction rdf:resource="http://www.jimmywales.com/aus_img_small.jpg" />
        <foaf:interest rdf:resource="http://www.wikimedia.org"
                       rdfs:label="Wikipedia" />
        <foaf:knows>
            <foaf:Person>
                <foaf:name>Angela Beesley</foaf:name> 
                <!-- Wikimedia Board of Trustees -->
            </foaf:Person>
        </foaf:knows>
    </foaf:Person>
</rdf:RDF>

[edit] See also

• Resource Description Framework (RDF)
• Web Ontology Language (OWL)
• Semantic Web
• Description of a Career (DOAC)
• Description of a Project (DOAP)
• Semantically-Interlinked Online Communities (SIOC)
• hCard (HTML vCard)
• XHTML Friends Network (XFN)

[edit] External links

• The FOAF Project
• FOAF specification
• FOAF+DOAC Project Homepage
• Foaf-O-matic Web application allowing loading/editing and generation of FOAF Profiles integrating globally unique identifiers
• FOAF dataset a dataset of 201,612 FOAF triples
• Finding friends with XML and RDF, from IBM
• Social Graph API - Google indexes pages embedded with XFN or FOAF tags and provides API for aggregating the results.

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