"The Web is quickly becoming the world's fastest growing repository of data," explained Tim Berners-Lee, W3C director. "RDF provides the necessary foundation and infrastructure to support the description and management of this data. RDF can transform the Web into a more useful and powerful information resource."
The World Wide Web was originally built for human consumption, and although everything on it is machine-readable, this data is not machine-understandable. It is very hard to automate anything on the Web, and because of the volume of information the Web contains, it is not possible to manage it manually. The solution proposed here is to use metadata to describe the data contained on the Web.
Metadata is "data about data." For example, a library catalog is metadata, since it describes publications or specifically in the context of this specification "data describing Web resources". The distinction between "data" and "metadata" is not an absolute one; it is a distinction created primarily by a particular application, and many times the same resource will be interpreted in both ways simultaneously. Examples of metadata that will be exchanged using RDF include "Title", "Author" (or "Creator"), "Publisher", and "Format".
RDF provides interoperability between applications that exchange machine-understandable information on the Web. RDF emphasizes facilities to enable automated processing of Web resources. RDF can be used in a variety of application areas; for example: in resource discovery to provide better search engine capabilities, in cataloging for describing the content and content relationships available at a particular Web site, page, or digital library, by intelligent software agents to facilitate knowledge sharing and exchange, in content rating, in describing collections of pages that represent a single logical "document", for describing intellectual property rights of Web pages, and for expressing the privacy preferences of a user as well as the privacy policies of a Web site. RDF with digitally signed documents will be key to building the "Web of Trust" for electronic commerce, collaboration, and other applications.
"RDF has a general-purpose design and we are pleased that it is already being applied in areas we did not originally anticipate. Sophisticated applications of RDF may combine metadata about the same object supplied by more than one party on the Web, selecting the optimal source for specific properties and merging the sources' expertise."
Bob Schloss, IBM, W3C RDF Working Group co-chair
Resource Description Framework (RDF) uses the W3C's Extensible Markup Language (XML) to define a foundation for processing metadata and complements XML. Whereas XML can be used as a general way to transport data on the Web given prior agreement between the parties on the specific form of the data to be transported, RDF layers on top of XML a general form for a broad category of data. When the XML data is declared to be of the RDF format, applications will be able to understand much of the interpretation of the data without prior arrangement. This gives Web users the benefit of generic metadata processing tools that will be reuseable across a variety of metadata application domains.
As a result of many communities coming together and agreeing on basic principles of metadata representation and transport, RDF has drawn influence from several different sources. The main influences have come from the Web standardization community itself in the form of HTML metadata and PICS, the library community, the structured document community in the form of SGML and more importantly XML, and also the knowledge representation (KR) community. There are also other areas of technology that contributed to the RDF design; these include object-oriented programming and modeling languages, as well as databases.
"The cooperation of experts from several metadata communities in the design of RDF, including libraries, content providers, commercial software vendors and academics, will result in a steady improvement in the value of the World Wide Web as a global information resource."
Eric Miller, OCLC, W3C RDF Working Group co-chair
For more information on RDF, see http://www.w3.org/RDF
The W3C was created to lead the Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability. It is an international industry consortium jointly run by the MIT Laboratory for Computer Science (LCS) in the USA, the National Institute for Research in Computer Science and Control (INRIA) in France and Keio University in Japan. Services provided by the Consortium include: the development of open, industry standard specifications; a repository of information about the World Wide Web for developers and users; reference code implementations to embody and promote standards; and various prototype and sample applications to demonstrate use of new technology. To date, more than 300 organizations are Members of the Consortium.
For more information about the World Wide Web Consortium, see http://www.w3.org/