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Unformatted text preview: . . Winter 2008 CPE/CSC 366: Database Modeling, Design and Implementation Alexander Dekhtyar . . XML in a Nutshell XML , e X tended M arkup L anguage is a collection of rules for universal markup of data. Brief History XML has two predecessors: SGML. SGML stands for Standard Generalized Markup Language. It was designed in late 1980s for document markup. SGML has a large spec- ification and a set of complicated rules for dealing with exceptional cases of document markup. SGML was the first language that used the “angle bracket” syntax for markup elements: ‘‘<a>", ‘‘<b>" , etc. SGML does not define a specific set of markup elements (tags), rather it specifies the rules for creation of markup languages. HTML. HTML is a specific markup language designed for the purpose of directing the rendering of the content of web pages. Unlike SGML, HTML does have a specific set of tags. XML combines two important features of these languages: • Flexibility of SGML: like SGML, XML is a set of rules for defining a specific markup langauge. It allows interested parties to create their own markup language and use it for marking up any data. • Simplicity of HTML: like HTML, and unlike SGML, XML specifica- tion is quite simple, and easy-to-understand. XML is much easier to use than SGML (technically, XML is a proper subset of SGML spec.). 1 The XML specification has been developed and maintained by the World Wide Web Consortium (W3C) ( http://www.w3.org ). The first W3C Recom- mendation (the official name of the final technical specifications released by W3C) appeared in 1998. XML Syntax XML documents consist for the following: • XML version identification. The first line of any XML document iden- tifies it as an XML document, specifies the XML version it complies to, and identifies any other potential information useful for automated processing of XML documents. A simple first line looks as follows:processing of XML documents....
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- Spring '08
- Databases, XML Schema