OWL 2: Knowledge and Data on Web Scale
OWL 2 Connects the Web of Knowledge with the Web of Data
Ian Jacobs, <email@example.com>, +1.718.260.9447
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http://www.w3.org/ -- ?? October 2009 -- Today W3C announces an important revision and extension of the Web Ontology Language (OWL). OWL 2 is a Semantic Web standard that provides a framework for asset management, enterprise integration, and the sharing and reuse of data on the Web. This standard format for information sharing spans application, enterprise, and community boundaries - all of these different types of "user" can share knowledge and data, even if they don't share the same software. As well as extended representational capabilities, OWL 2 provides several profiles that allow for more simple implementations and greatly improved scalability. OWL 2 therefore brings the Semantic Web closer to its full potential by connecting the web of knowledge with the web of data.
OWL 2 provides increased expressive power and improved scalability
OWL 2 provides a powerful language for defining ontologies -- vocabularies where the meaning of each term is precisely defined. They are used to classify the terms used in a particular application, characterize possible relationships, and define possible constraints on using those relationships.
An example may help. A bookseller may want to integrate data coming from different publishers. The data can be imported into a common model, eg, by using converters to the publishers’ databases. However, one database may use the term “author”, whereas the other may use the term “creator”. To make the integration complete, and extra “glue” should be added to the data integration process, describing the fact that the relationship described as “author” is the same as “creator”. One may also want to specify when the data on two, say, authors refer to the same persons (e.g., if the recorded names and social identification numbers are identical). If these facts are described in precise, formal terms, generic processors may infer extra information from the data (like that two author references, coming from different publishers, refer in fact to the same person). These extra pieces of information form, in fact, an ontology, albeit an extremely simple one. OWL allows to build such vocabularies, whether simple ones with only a few terms, or very complex ones involving several thousands of terms.
W3C has published a first version of OWL in 2004; this technology has already been successfully deployed in such diverse application areas as Oil & Gas exploration, eBusiness, health record management, semantic desktops, or management of musical archives (see, for example, some of the Semantic Web Use Cases and Case Studies published at W3C).
OWL 2 is an extension of OWL, adding some new features that have been requested by users. These include, for example, a greatly extended support for datatypes (users can now characterise literal values as boolean, as binary data, as time instants, as different types of numerical values, and even restrictions on like numeric intervals, or strings with particular length), extended annotation capabilities on the vocabulary definitions, better ways of identification of resources (eg, the example above on personal data being used to identify persons).
An important feature of OWL 2 is the introduction of Profiles. The full implementation of an OWL aware software may be costly, both in complexity and usage. The OWL 2 specification includes therefore a number of profiles, essentially sub-languages of OWL, that are much easier to implement and deploy, or that can be much more efficient in usage. Applications, vocabularies, ontologies may restrict themselves to those sub-languages in return for more efficients implementations.
Finally, in addition to the above mentioned feature enhancements, the specification itself has also been extensively revised and improved with respect to both clarity and precision.
To get started with OWL, see the OWL Overview and OWL Primer.