Tim Berners-Lee, director of the World Wide Web Consortium (W3C), states that, “The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in cooperation” (Berners-Lee, 2001). The Semantic Web will bring structure to the meaningful content of Web pages, creating an environment where software agents, roaming from page to page, can readily carry out sophisticated tasks for users. The Semantic Web (SW) is a vision of the Web where information is more efficiently linked up in such a way that machines can more easily process it. It is generating interest not just because Tim Berners-Lee is advocating it, but because it aims to solve the problem of information being hidden away in HTML documents, which are easy for humans to get information out of but are difficult for machines to do so. We will discuss the Semantic Web here.
Key Terms in this Chapter
Dublin Core: A set of basic metadata properties (such as title) for classifying Web resources.
Standard Generalized Markup Language (SGML): An international standard in markup languages, a basis for HTML, and a precursor to XML. SGML is both a language and an ISO standard for describing information embedded within a document.
World Wide Web Consortium (W3C): A neutral meeting of those to whom the Web is important, with the mission of leading the Web to its full potential. It was established in 1994 to lead the Web to its full potential by developing common standards.
Document Type Definition (DTD): A DTD is a metadocument containing information about how a given set of SGML tags can be used. In the XML world this role will be taken over by a schema.
The Resource Description Framework (RDF): The resource description framework is a markup language for describing information and resources on the Web. The RDF metadata model is based upon the idea of making statements about resources in the form of a subject-predicate-object expression, called a triple in RDF terminology. The subject is the resource, the “thing” being described. The predicate is a trait or aspect about that resource, and often expresses a relationship between the subject and the object. The object is the object of the relationship or value of that trait.
Web Ontology Language (OWL): OWL is a semantic markup language for publishing and sharing ontologies on the World Wide Web. OWL developed as a vocabulary extension of RDF (the resource description framework) and is derived from the DAML+OIL Web ontology language.
Semantic Web: The Semantic Web is a Web that is able to describe things in a way that computers can understand such as U” being a rock band from Dublin, Ireland. Statements are built with syntax rules. The syntax of a language defines the rules for building the language statements.
Metadata: Data about data on the Web, including, but not limited to, authorship, classification, endorsement, policy, distribution terms, IPR, etc. Some metadata, such as file dates and sizes, can easily be seen by users; other metadata can be hidden or embedded and unavailable to users who are not technically adept. Metadata is generally not reproduced in full form when a document is printed.
Universal Resource Identifier (URI): The string (often starting with http) comprising a name or address that can be used to refer to a resource. It is a fundamental component of the World Wide Web.