Web of Linked Data

Here follows a quick introduction to the notions of Semantic Web, Linked Data and the Linking Open Data initiative.

Semantic Web

The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries. This fosters the opportunity of creating a next generation world-wide web of structured data which are not only understandable to humans (like the typical HTML page), but also understandable by computers.

The data on the Semantic Web have explicitly defined structure (like in the databases) and semantics (like in the ontologies). This allows the computers to perform structured queries (like those in SQL) and infer new facts.

In short, the Semantic Web is an extension of the current WWW, in which information is given well-defined meaning, better enabling computers and people to work in cooperation.

Linked Data

The web of linked data represents a vision of Tim Berners-Lee of a collection of open and linked structured data on the Web. It calls upon two initiatives: (a) the Linked Data initiative and (b) the Linking Open Data initiative.

Linked Data is a set of principles for publishing of structured data in the form of RDF graphs, so that they can be explored and navigated in a manner analogous to the HTML WWW and be understandable by computers. These principles are:

• 1. Using URIs as names of things
• 2. Using HTTP URIs, so that people can look up those names
• 3. Providing useful information when someone looks up a URI
• 4. Including links to other URI, so people can discover more things

  The linked data concept is an enabling factor for the realization of the Semantic Web as a global web of structured data.

  Linking Open Data (LOD)

  Linking Open Data (LOD) is a W3C SWEO community project. It aims to facilitate the emergence of a web of linked data, by means of publishing and interlinking open data on the Web in RDF.

  The central dataset of LOD is DBpedia - an RDF extract of the Wikipedia. DBpedia is a sort of a hub in the LOD graph, which guarantees certain level of connectivity. It also provides easy entry points to find resources of interest using their Wikipedia names in DBpedia and through it in the LOD network.