FOAF and representing identity information

The Friend of a Friend (FOAF) ontology is currently one of the most successful, accepted and popular Semantic Web projects. It offers a wide, standard vocabulary for representing people and organizations in a social context. Via the use of identity ontologies such as FOAF, it is possible to promote a paradigm shift and hand identity control over to the users.

Social networks generally use one of two methods of access to personal data, apart from their graphical interfaces:

1. The automatic generation of FOAF profiles with an RDF/XML syntax: Some social networks automatically generate an instance of the user profile in FOAF, although the ontology is not always strictly followed or the classes and properties are used in a different way. Proofile, LiveJournal, Vox, CrazyLife, Origo, e-Cademy and Hi5 use this method.
2. Access to attributes via an API: Facebook (via the F8 API) and Orkut (via the OpenSocial API) use this method. A REST interface is normally used.

Exhaustive analysis and experimentation with the F8 and OpenSocial APIs has led to two conclusions:

• The percentage of useful information directly mappable to the FOAF ontology is 42% for F8 and 38% for OpenSocial.
• There is useful information provided by the APIs not mappable to FOAF that can be represented using other ontologies, such as DOAC, Dublin Core and vCard.