Semantic Web
Abstract:
The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries. It is a collaborative effort led by W3C with participation from a large number of researchers and industrial partners.The Semantic Web is a Web of data. There is a lot of data we all use every day, and it's not part of the Web. For example, I can see my bank statements on the web, and my photographs, and I can see my appointments in a calendar. But can I see my photos in a calendar to see what I was doing when I took them? Can I see bank statement lines in a calendar? Why not? Because we don't have a web of data. Because data is controlled by applications, and each application keeps it to itself.
The Semantic Web is an idea of World Wide Web inventor Tim Berners-Lee that the Web as a whole can be made more intelligent and perhaps even intuitive about how to serve a user's needs. Berners-Lee observes that although search engines index much of the Web's content, they have little ability to select the pages that a user really wants or needs. He foresees a number of ways in which developers and authors, singly or in collaborations, can use self-descriptions and other techniques so that context-understanding programs can selectively find what users want.
How Semantic Web Works
The World Wide Web is an interesting paradox -- it's made with computers but for people. The sites you visit every day use natural language, images and page layout to present information in a way that's easy for you to understand. Even though they are central to creating and maintaining the Web, the computers themselves really can't make sense of all this information. They can't read, see relationships or make decisions like you can.
The Semantic Web proposes to help computers "read" and use the Web. The big idea is pretty simple -- metadata added to Web pages can make the existing World Wide Web machine readable. This won't bestow artificial intelligence or make computers self-aware, but it will give machines tools to find, exchange and, to a limited extent, interpret information. It's an extension of, not a replacement for, the World Wide Web.
That probably sounds a little abstract, and it is. While some sites are already using Semantic Web concepts, a lot of the necessary tools are still in development. In this article, we'll bring the concepts and tools behind the Semantic Web down to earth by applying them to a galaxy far, far away.
Abstract:The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries. It is a collaborative effort led by W3C with participation from a large number of researchers and industrial partners.The Semantic Web is a Web of data. There is a lot of data we all use every day, and it's not part of the Web. For example, I can see my bank statements on the web, and my photographs, and I can see my appointments in a calendar. But can I see my photos in a calendar to see what I was doing when I took them? Can I see bank statement lines in a calendar? Why not? Because we don't have a web of data. Because data is controlled by applications, and each application keeps it to itself.
Introduction:
(Image source: Wikipedia)
Reasoners that can process Ontologies and data to create new knowledge that did not exist before. For example, figuring out all the people who work for subsidiaries of a given parent company without that fact ever being explicitly tagged.
Query tools like SPARQL that can be used to query this stored/generated knowledge.
Whilst the term itself is somewhat vague, the key elements of the Semantic Web that programmers should understand are :-
Tagged data - typically using the Resource Description Framework (RDF) or Microformats. These make web pages understandable by computers. The word "W3C" for example might be tagged as an "Organization" rather than a "Website".
Ontologies defining relationships between entities using the Web Ontology Language (OWL), N3, Turtle, N-Triples, ... An Ontology defines things such as classes, superclasses, subclasses, properties and the relationships between them. For example it might specify that "if a person works for a company then the company employs the person" (an inverse relationship). Ontologies are normally represented using triples which have a Subject, a Predicate and an Object. The real twist here is that Predicates can also be used as the Subject or Object of any other statement in the Ontology. For example you can define what 'inverse' or 'reflexive' mean using the same language that you use to define that person X works for company Y!
Ontologies defining relationships between entities using the Web Ontology Language (OWL), N3, Turtle, N-Triples, ... An Ontology defines things such as classes, superclasses, subclasses, properties and the relationships between them. For example it might specify that "if a person works for a company then the company employs the person" (an inverse relationship). Ontologies are normally represented using triples which have a Subject, a Predicate and an Object. The real twist here is that Predicates can also be used as the Subject or Object of any other statement in the Ontology. For example you can define what 'inverse' or 'reflexive' mean using the same language that you use to define that person X works for company Y!
Reasoners that can process Ontologies and data to create new knowledge that did not exist before. For example, figuring out all the people who work for subsidiaries of a given parent company without that fact ever being explicitly tagged.
Query tools like SPARQL that can be used to query this stored/generated knowledge.
The World Wide Web is an interesting paradox -- it's made with computers but for people. The sites you visit every day use natural language, images and page layout to present information in a way that's easy for you to understand. Even though they are central to creating and maintaining the Web, the computers themselves really can't make sense of all this information. They can't read, see relationships or make decisions like you can.
The Semantic Web proposes to help computers "read" and use the Web. The big idea is pretty simple -- metadata added to Web pages can make the existing World Wide Web machine readable. This won't bestow artificial intelligence or make computers self-aware, but it will give machines tools to find, exchange and, to a limited extent, interpret information. It's an extension of, not a replacement for, the World Wide Web.
That probably sounds a little abstract, and it is. While some sites are already using Semantic Web concepts, a lot of the necessary tools are still in development. In this article, we'll bring the concepts and tools behind the Semantic Web down to earth by applying them to a galaxy far, far away.
Reference:
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