Download 8. An Overview of Extensible Markup Language (XML)

An Overview of Extensible Markup Language
8. An Overview of Extensible Markup Language (XML)
8.1 Introduction to XML
XML is a new standard approved by the W3C (http://www.w3.org/XML). It roots
go back to 1969, Charles Goldfarb, IBM researcher who in charge of the
Generalized Markup Language (GML) team
• Its predecessor: Standard Generalized Markup Language (SGML)
• Another file format for storing information in hierarchical formats
• Promises to increase both the efficiency and the flexibility of handling
computerized information as needed in E-Commerce, for example you can
specify a set new user defined tags: <PRICE> and </PRICE> that is
unique to specific applications and is not limited by the tags available from
HTML.
• A XML document is saved with .xml as extension
• It can describe both themselves and their content
• An XML parser is required to interpret and display the document
An XML-compliant application will process the following three files to display XML
content:
• The XML document
o Containing document data
o xml is used as the extension of the file name
• A style sheet
o Document display formatting rules for browsers
o The file is saved with .css as the extension
• Document Type Definition (DTD)
o A rule file specifies how XML document elements, attributes, and
other data
o The file is saved with .dtd as the extension
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An Overview of Extensible Markup Language
8.2 XML Resources
XML Applications:
• http://www.HL7.org (The Health Level Seven Organization Protocol)
• http://www.ansi.org (ANSI Web site)
• http://www-4.ibm.com/software/ad/features/xmi.html
• http://www.w3.org/Math/ MathML (a XML-based Math Markup
Language)
• http://xml-cml.org (Chemical Markup Language)
• http://www.venus.co.uk/omf/ChemML (a XML-based Chemestry Markup
Language)
• http://www.stars.com/Seminars/Language/OSD.html (Open Software
Description)
• http://www.ofx.net/ofx/default.asp (Open Financial Exchange)
XML Resources:
• http://www.ucc.ie/xml/
(The XML FAQ)
• http://www.sil.org/sgml/xml.html (The SGML/XML Web Pages)
• http://www.xml.com
(XML.com)
• http://www.xmlx.com
(The XML Exchange)
• http://www.w3.com
(The World Wide Web Consortium)
• http://xmlinfo.com
(XML info)
Development tools
• Text editors (Notepad)
• Word processors with XML capabilities (Microsoft Word, Corel
WordPerferct)
• Parsers (built-in browser)
• Specialized XML development tools:
o XML Pro (www.vervet.com)
o Microsoft's XML Notepad (www.microsoft.com/xml/notepad/)
o Visual XML (www.pierlou.com/visxml/)
o XMLSpy (www.icon-is.com)
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An Overview of Extensible Markup Language
8.3 XML Terminology
• A XML document consists of one or more user defined elements
• Each element has two tags: opening tag, and closing tag
• Each element can have attributes
• Empty element has no text appearing between two tags
• Syntax:
Start Tag:<ElementName AttributesName="AttributeValue">
End Tag: </ElementName>
• Examples of elements:
<PRICE Currency="Euro"> 26.02 </PRICE>
<PICTURE>
</PICTURE>
<ARTICLE>
<TITLE>
</TITLE>
<DATE>
</DATE>
<AUTHOR>
<FIRSTNAME> </FIRSTNAME>
<LASTNAME> </LASTNAME>
</AUTHOR>
<SUMMARY>
</SUMMARY>
<CONTENT>
</CONTENT>
</ARTICLE>
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