Rule 3: Useful Information
When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL) Other Information:
The third rule, that one should serve information on the web against a URI, is, in 2006, well followed for most ontologies,
but, for some reason, not for some major datasets. One can, in general, look up the properties and classes one finds in data,
and get information from the RDF, RDFS, and OWL ontologies including the relationships between the terms in the ontology.
The basic format here for RDF/XML, with its popular alternative serialization N3 (or Turtle). Large datasets provide a SPARQL
query service, but the basic linked data should br provided as well. Many research and evaluation projects in the few years
of the Semantic Web technologies produced ontologies, and significant data stores, but the data, if available at all, is buried
in a zip archive somewhere, rather than being accessible on the web as linked data. The Biopax project, the CSAktive data
on computer science research people and projects were two examples. [The CSAktive data is now (2007) available as linked data]
There is also a large and increasing amount of URIs of non-ontology data which can be looked up. Semantic wikis are one example.
The "Friend of a friend" (FOAF) and Description of a Project (DOAP) ontologies are used to build social networks across the
web. Typical social network portals do not provide links to other sites, nor expose their data in a standard form. LiveJournal
and Opera Community are two portal web sites which do in fact publish their data in RDF on the web. (Plaxo has a trail scheme,
and I'm not sure whether they support knows links). This means that I can write in my FOAF file that I know Håkon Lie by using
his URI in the Opera Community data, and a person or machine browsing that data can then follow that link and find all his
friends. [Update:] Also, the Opera Community site allows you to register the RDF URI for yourelf on another site. This means
that public data about you from different sites can be linked together into one web, and a person or machine starting with
your Opera identity can find the others.
Objective(s):
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