XML News from Thursday, January 3, 2008

The W3C has published the first working draft of Cool URIs for the Semantic Web:

The Semantic Web is envisioned as a decentralised world-wide information space for sharing machine-readable data with a minimum of integration costs. Its two core challenges are the distributed modelling of the world with a shared data model, and the infrastructure where data and schemas can be published, found and used. A basic question is thus how to publish information about resources in a way that allows interested users and software applications to find them.

On the Semantic Web, all information has to be expressed as statements about resources, like the members of the company Example.com are Alice and Bob or Bob's telephone number is "+1 555 262 or this Web page was created by Alice. Resources are identified by Uniform Resource Identifiers (URIs) [RFC3986]. This modelling approach is at the heart of Resource Description Framework (RDF) [RDFPrimer].

Using RDF, the statements can be published on the website of the company. Others can read the data and publish their own information, linking to existing resources. This forms a distributed model of the world.

At the same time, Web documents have always been addressed with URIs (in common parlance often referred as Uniform Resource Locators, URLs). This is useful because it means we can easily make RDF statements about Web pages, but also dangerous because we can easily mix up Web pages and the things, or resources, described on the page.

So the question is, what URIs should we use in RDF? As an example, to identify the frontpage of the Web site of Example Inc., we may use http://www.example.com/. But what URI identifies the company as an organisation, not a Web site? Do we have to serve any content—HTML pages, RDF files—at those URIs? In this document we will answer these questions according to relevant specifications. We explain how to use URIs for things that are not Web pages, such as people, products, places, ideas and concepts such as ontology classes. We give detailed examples how the Semantic Web can (and should) be realised as a part of the Web.