InfoMedia Inc.

What is RDF?

Resource Definition Format, a W3C recommendation.
Provides a lightweight ontology system to support the exchange of knowledge on the Web.
Enables the modeling and imposition of descriptive metadata onto Web resources.
An simple but powerful abstract model for knowledge representation.
An XML interchange syntax.
Designed initially as a way to describe and catalog information and resources on Web sites.
Can be used for general cataloging purposes (e.g., RedHat's RPM description documents).

Benefits:

Application Development

Provides a standard format for representing metadata for interchange or import.
RDF implementations provide metadata representation services.

Searching Data

Enables searching across Web resources using RDF-defined metadata.
Can augment standard Web search engines by providing additional metadata.
Can result in more precise search results.

How It Works:

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.
For describing intellectual property rights of Web pages.
For expressing the privacy preferences of a user as well as the privacy policies of a Web site.

RDF with digital signatures will be key in building the "Web of Trust" for electronic commerce, collaboration, and other applications.

Resource Description Framework (RDF) is based on Web technologies and, as a result, is lightweight and highly deployable. RDF provides interoperability between applications that exchange metadata and is targeted for many application areas including; resource description, site-maps, content rating, electronic commerce, collaborative services, and privacy preferences. RDF is the result of members of these communities reaching consensus on their syntactical needs and deployment efforts.

RDF is an application of XML (W3C, 1998b). It extends the XML model and syntax to be specific for describing resources. RDF utilizes the Namespace facility of XML (W3C, 1999b). The XML Namespace, which points to a URI, allows RDF to scope and uniquely identify a set of properties. This set of properties, called a schema, can be accessed at the URI identified by the namespace. Also, since RDF is based on XML, it inherits the language tag, thus enabling the support of multi-lingual metadata.

The objective of RDF is to support the interoperability of metadata. RDF allows descriptions of Web resources—any object with a Uniform Resource Identifier (URI) as its address—to be made available in machine understandable form. This enables the semantics of objects to be expressible and exploitable. Once deployed, this will enable services to develop processing rules for automated decision-making about Web resources.

The broad goal of RDF is to define a mechanism for describing resources that makes no assumptions about a particular application domain, nor defines (a priori) the semantics of any application domain. The definition of the mechanism should be domain neutral, yet the mechanism should be suitable for describing information about any domain.

RDF is similar in many ways to the XML Topic Maps specification. There has been and continues to be a great deal of work to understand the relationship of these two standards to each other. All of this work is being done more or less in the context of the W3C's semantic Web activity.

RDF has also been used as the basis for a more specialized knowledge representation language, DARPA Agent Markup Language (DAML), developed by the United States Defense Advanced Research Projects Agency (DARPA). DAML adds to RDF a number of specialized structures for representing knowledge in a way that is directly useful to expert systems and other forms of artificial intelligence systems.