This article introduces Resource Description Framework (RDF), developed by the W3C for Web-based metadata, using XML as an interchange syntax. RDF's essential aim is to make work easier for autonomous agents, which would refine the Web by improving search engines and service directories. Author Uche Ogbuji gives an overview of RDF aspects from schemas to usage scenarios. The article assumes that you are already familiar with XML.

Suppose you're designing an XML application or maybe just writing a DTD or schema. You've followed various best practices about element and attribute names, when to use elements versus attributes, and other design issues, because you want your XML to be useful in the widest variety of situations.

The creation of RDF raises the prospect of a widely accepted standard for representing expressive declarative knowledge on the Web. However, just representing knowledge and information is not enough: users as well as information agents have to query and use the data in several ways. An RDF Query specification would allow a range of applications to exploit any information source which can be represented in terms of the RDF data model.

Over recent months, members of the www-rdf-interest mailing list have been working at creating practical applications of RDF technology. Notable among these efforts have been Dan Connolly's work with using XSLT to generate RDF from web pages, and R.V. Guha's lightweight RDF database project.

Many Semantic Web advocates have gone out of their way to disassociate their visions and projects from the Artificial Intelligence moniker. No surprise, since the AI label has been the kiss of, if not death, at least scorn, since Lisp machines were frozen out of the marketplace during the great "AI winter" of the mid-1980s. Lisp still suffers from its association with the AI label, though it does well by being connected with the actual technologies.

RDF is like my eccentric old uncle. I don't know him as well as I'd like, which is partly his fault, since his eccentricities can be off-putting. Of course they're what make him so interesting and are the reason I want to get to know him better in the first place. Yeah, RDF is just like that.

Edd Dumbill explores an XML and RDF application known as Friend-of-a-Friend (FOAF). FOAF allows the expression of personal information and relationships, and is a useful building block for creating information systems that support online communities. Code samples demonstrate the basics.

RDF is the latest acronym to add to your list, one that is set to gain in significance in the future. At present though it is early days for RDF and little accessible information is available for the interested reader. This short summary will try to outline some key points regarding RDF and point to available further information. What is certain is that this summary will go out of date quickly, RDF is 'work in progress' and is an area which is undergoing rapid development and change.