W3C completes framework for the Semantic Web
Lot of work to be done
The World Wide Web Consortium (W3C) has announced final approval of two key technologies for the Semantic Web. These are the revised Resource Description Framework (RDF) and the Web Ontology Language (OWL).
These are important components for the Semantic Web that will make it possible for the Web to respond more intelligently to people's information needs. The powerful ideas behind the Semantic Web are highly relevant to enterprise's internal needs and can be expected to cross over as have Instant Messaging and Blogging, to name just a couple of Internet technologies that are changing the enterprise's approach to information handling.
The Semantic Web uses three key technology standards: XML to provide the rules and syntax to define structured documents, RDF to define a vocabulary framework for describing document properties and OWL to define an area of knowledge.
Today, XML is the most mature and widely-used of these standards. It provides a set of rules to define and communicate the structure of both documents and data. However although XML supplies a powerful, flexible syntax to define structured documents it does not define their meaning.
The next standard, RDF, provides a set of rules for describing the semantics or meaning of documents. Just as XML provides a way to describe the structure of a document, RDF provides the means to define its characteristics or properties. The RDF syntax links Resources and Properties into Statements:
- A Resource is anything that can have a URI (uniform resource identifier); this includes Web pages as well as individual elements of an XML document.
- A Property is a Resource that has a name and is used to indicate a property of a document such as its Author or Title.
- A Statement combines a Resource, a Property, and a value, for example, "The Author of article id #3756" is Martin Langham."
An RDF Schema combines these descriptions into sets of Vocabularies which would be used for a similar group of documents such as a library catalogue, a repository of HR documents, engineering drawings and so on. Independent parties will be able to exchange vocabularies and use the same Property descriptions. RDF based vocabularies will become important commercial assets and we can expect that certain vocabularies will become dominant in an application area as each information user starts to use the same language.
RDF is not sufficient to support the requirements of the Semantic Web by itself. The relationships between a collection of documents needs to be described to enable computers to provide various kinds of reasoning services about the domain and the knowledge described. For this task an ontology is needed that describes and represents an area of knowledge. Ontology is a term borrowed from philosophy that refers to the science of describing the kinds of entities in the world and how they are related.
An ontology language is used to formally describe a knowledge domain including: what individuals and classes of individuals there are in that domain and the relationships between these individuals and classes. Ontology languages are used by people and applications that need to process subject-specific information - for example in finance, education, construction, etc.
OWL the Web Ontology Language recently released by the W3C provides a language for defining Web-based ontologies. OWL defines classes of documents and their properties and the constraints on the way those classes and properties can be related. OWL builds additional syntax on top of RDF and RDF Schemas for describing Properties and the relations between Classes.
Now that the three standards for defining the Semantic Web are available, a lot of work will be needed to create the RDF schemas and ontologies to make the Semantic Web a reality. These technology standards may appear arcane to enterprise information users but they have the same potential as Web services to revolutionise the way that we can use information to get the job done.