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An Introduction to the Semantic Web

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An Introduction to the Semantic Web An Introduction To The Semantic Web Fernando de Souza 1 “The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation.” Tim Berners-Lee, James Hendler and Ora Lassila, The Semantic Web, Scientific American, May 2001 2 1 An Introduction To The Semantic Web …extension of the current web… “. .information on the web needs to be in a form that machines can ‘understand’ rather than simply display. The concept of machine-understandable documents does not imply some magical artificial intelligence allowing machines to comprehend human mumblings. It relies solely on a machine’s ability to solve well-defined problems by performing well- defined operations on well-defined data.” From Berners-Lee, Hendler; Nature, 2001 3 http://www.nature.com/nature/debates/e-access/Articles/bernerslee.htm …extension of the current web… “Most of the Web's content today is designed for humans to read, not for computer programs to manipulate meaningfully.” Tim Berners-Lee, James Hendler and Ora Lassila, The Semantic Web, Scientific American, May 2001 4 2 An Introduction To The Semantic Web …well-defined meaning… There are lots of ways in which our machines can use our web content when they can understand it. •When my personal digital assistant's calendar program understands dates, it can alert me when an appointment is coming up. •When my email program's address book understands that something is a phone number or an email address, it can set up communication with that person with a click. •When my digital phone is given a location in Japan, it can access a program to compute which trains to take and how much it will cost. Tim Berners-Lee, James Hendler and Ora Lassila, The Semantic Web, Scientific American, May 2001 5 …well-defined meaning… … you want to search online catalogs from different manufactures for equivalent replacement parts for a Volvo 740. The raw information that may answer these questions, may indeed be on the Web, but it's not in a machine-usable form. You still need a person to discern the meaning of the information and its relevance to your needs. The Semantic Web addresses this problem in two ways. it will enable communities to expose their data so that a program doesn't have to strip the formatting, pictures and ads from a Web page to guess at the relevant bits of information. it will allow people to write (or generate) files which explain - to a machine - the relationship between different sets of data. one will be able to make a 'semantic link' between a database with a 'zip-code' column and a form with a 'zip' field that they actually mean the same thing. This will allow machines to follow links and facilitate the integration of data from many different sources. Berners-Lee, Tim and Eric Miller, The Semantic Web lifts off 6 http://www.ercim.org/publication/Ercim_News/enw51/berners-lee.html 3 An Introduction To The Semantic Web …well-defined meaning… Semantic metadata: Metadata that describe contextually relevant or domain- specific information about content (in the right context) based on a custom (e.g., industry-specific or enterprise specific) metadata model or ontology is known as semantic metadata. For example, if the content is from the business domain, the relevant semantic metadata could be company name, ticker symbol, industry, sector, executives, etc., whereas if the content is from the Intelligence domain, the relevant semantic metadata could be terrorist name, event, location, organization, etc. Metadata elements that offer greater depth and more insight ‘about the document’ fall under the semantic metadata category. In contrast, syntactic metadata focuses on elements such as size of the document, location of a document, or date of document creation that do not provide a level of understanding about what the document says or implies. Amit Sheth , Semantic Metadata 7 http://www.semagix.com/documents/DM-Review-Final.pdf …well-defined meaning… Web of Knowledge Proof, Logic and Ontology Languages (e.g., DAML+OIL) Shared terms/terminology Machine-Machine communication 2010 Resource Description Framework (RDF) eXtensible Markup Language (XML) Self-Describing Documents 2000 HyperText Markup Language (HTML) Formatted Documents HyperText Transfer Protocol Foundation of the Current Web (HTTP) 1990 From Berners-Lee, Hendler; Nature, 2001 8 http://www.nature.com/nature/debates/e-access/Articles/bernerslee.htm 4 An Introduction To The Semantic Web …computers and people to work in cooperation… “In the next step, the Semantic Web will break out of the virtual realm and extend into our physical world. URIs can point to anything, including physical entities, which means we can use the RDF language to describe devices such as cell phones and TVs.” Tim Berners-Lee, James Hendler and Ora Lassila, The Semantic Web, Scientific American, May 2001 9 …computers and people to work in cooperation… “… the new technology, like the old, involves asking people to make some extra effort, in repayment for which they will get substantial new functionality -- just as the extra effort of producing HTML markup (HyperText Markup Language) is outweighed by the benefit of having content searchable on the web.” From Berners-Lee, Hendler; Nature, 2001 10 http://www.nature.com/nature/debates/e-access/Articles/bernerslee.htm 5 An Introduction To The Semantic Web “Once you have a truly massive amount of information integrated as knowledge, then the human-software system will be superhuman, in the same sense that mankind with writing is superhuman compared to mankind before writing." Doug Lenat, June 21, 2001 http://www.cyc.com/cyc/company/about 11 Reference http://www.w3.org/2001/sw/ http://www.w3.org/DesignIssues/ http://www.w3.org/1998/02/Potential.html http://www.ontoportal.org.uk/snapshot/explore/themes/2/literature/28.html http://www.w3.org/TR/owl-features/ http://www-106.ibm.com/developerworks/xml/library/w-rdf/ http://www.semanticweb.org/ http://infomesh.net/2001/swintro/ 12 6 An Introduction To The Semantic Web 13 7.
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