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XMLExtensible Markup Language
XML
• The World Wide Web Consortium's (W3C's) XML Working Group developed XML (Extensible Markup Language),
– which is derived from Standard Generalized Markup Language (SGML),
– in 1996.
• XML is for electronic data exchange and storage.– A widely supported open technology (i.e., nonproprietary) – A language used to create other markup languages to describe
data in a structured manner.
What is XML?
• XML is the Extensible Markup Language.
– Language for creating markup languages• Mathematical formulas• Molecular structure of chemicals• Music• Recipes
– Create new tags• Used for Storing Data in structured manner.• Not a Formatting Language.• Describes data of virtually any type.
• Not just for Web pages.
• Defined by W3C to be application and vender neutral in 1996.
XML describes structure and semantics, not formatting
• XML documents contain only data and
• Structure markups,
• Not formatting.
• Formatting can be added with:– a browser that knows how to render these knew
marked-up data.
– a style sheet (css).
– an Extensible Stylesheet Language (XSL).
Article.xml
1 <?xml version = "1.0"?>
2
3 <!-- Fig. 20.1: article.xml -->
4 <!-- Article structured with XML -->
5
6 <article>
7
8 <title>Simple XML</title>
9
10 <date>September 19, 2001</date>
11
12 <author>
13 <firstName>Tem</firstName>
14 <lastName>Nieto</lastName>
15 </author>
16
17 <summary>XML is pretty easy.</summary>
18
19 <content>Once you have mastered XHTML, XML is easily
20 learned. You must remember that XML is not for
21 displaying information but for managing information.
22 </content>
23
24 </article>
XML declaration.Element article is the root element.
Elements title, date, author, summary and content are child elements of article.
Article.xml
1 <?xml version = "1.0"?>
2
3 <!-- Fig. 20.1: article.xml -->
4 <!-- Article structured with XML -->
5 <?xml-stylesheet type="text/css" href="article.css"?>
6 <article>
7
8 <title>Simple XML</title>
9
10 <date>September 19, 2001</date>
11
12 <author>
13 <firstName>Tem</firstName>
14 <lastName>Nieto</lastName>
15 </author>
16
17 <summary>XML is pretty easy.</summary>
18
19 <content>Once you have mastered XHTML, XML is easily
20 learned. You must remember that XML is not for
21 displaying information but for managing information.
22 </content>
23
24 </article>
Rendering XML documents using CSS“article.css”
title { display: block; font-family: Helvetica, Arial, sans; font-size: 32pt; font-weight: bold; text-align: center}
date { font-family: New York, Times New Roman, serif; font-size: 24pt; background-color: white; color: green; display: block } author { font-family: New York, Times New Roman, serif; font-size: 14pt; background-color: white; color: black; display: block }
content { font-family: courier; font-size: 14pt; background-color: white; color: blue }
Article.xml
1 <?xml version = "1.0"?>
2
3 <!-- Fig. 20.1: article.xml -->
4 <!-- Article structured with XML -->
5 <?xml-stylesheet type="text/css" href="article.xsl"?>
6 <article>
7
8 <title>Simple XML</title>
9
10 <date>September 19, 2001</date>
11
12 <author>
13 <firstName>Tem</firstName>
14 <lastName>Nieto</lastName>
15 </author>
16
17 <summary>XML is pretty easy.</summary>
18
19 <content>Once you have mastered XHTML, XML is easily
20 learned. You must remember that XML is not for
21 displaying information but for managing information.
22 </content>
23
24 </article>
Rendering XML documents using XSL“article.xsl”
<?xml version="1.0"?><xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl">
<xsl:template match="/"> <html> <body> <h1>
<font color="RED"> <xsl:value-of select="article"/>
</font> </h1> </body> </html> </xsl:template></xsl:stylesheet>
Create Markup
• XML permits document authors to create markup for virtually any type of information.
• This extensibility enables document authors to create entirely new markup languages for describing specific types of data, including
– mathematical formulas, – chemical molecular structures, – music, recipes, etc.
• Some XML-based markup languages include:– XHTML (Chapters 4 and 5), – MathML (for mathematics), – VoiceXMLTM (for speech), – SMILTM (Synchronous Multimedia Integration Language-for multimedia
presentations), – CML (Chemical Markup Language-for chemistry) and – XBRL (Extensible Business Reporting Language-for financial data
exchange).
Rendering: http://www.xml.com/style/
FO
IE
Amaya
XML Parser
• Processing an XML document requires a software program called an XML parser (or an XML processor).
• Most XML parsers are available at no charge and for a variety of programming languages (such as Java, python, C++, etc.).
• Parsers check an XML document's syntax and enable software programs to process marked-up data.
• XML parsers can support – the Document Object Model (DOM) or – the Simple API for XML (SAX).
DOM-based parsers• DOM-based parsers build tree structures containing XML document
data in memory.
• DOM-based parsers enable software programs to manipulate data in an XML document.
SAX-based parsers• SAX-based parsers process XML documents and generate events
when the parser encounters tags, text, comments, etc. – These events contain data from the XML document. – Software programs can "listen" for these events to obtain data from the
XML document.
• Several Independent Software Vendors have developed XML parsers, which can be found at
www.xml.com/xml/pub/Guide/XML_Parsers
XML document's structure
• An XML document optionally can reference a document that defines that XML document's structure.
• This document is either a Document Type Definition (DTD) or a schema.
• When an XML document references a DTD or schema, some parsers (called validating parsers) can read the DTD/schema and check that the XML document follows the structure that the DTD/schema defines.
• Parsers that cannot check for document conformity against DTD/schemas are nonvalidating parsers.
valid , nonvalid, well formed• If the XML document conforms to the DTD/schema (i.e.,
the document has the appropriate structure), the XML document is valid.
• If the XML document does not conform to the DTD/schema, the XML document is nonvalid.
• If an XML parser (validating or non-validating) can process an XML document successfully, that XML document is well formed (i.e., it is syntactically correct).
– By definition, a valid XML document also is well-formed.
Microsoft XML Validatorhttp://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/samples/internet/
xml/xml_validator/default.asp
• This sample web page allows you to enter in the URL of an XML document and both parse and validate that document.
CML
• CML Web based application – CML Molecules Viewer:
http://www.xml-cml.org/jumbo3/jumbo3-JS/jumbo.html
http://www.xml-cml.org/
http://www.xml-cml.org/jumbo3/jumbo3-JS/
SVG
• Scalable Vector Graphics (SVG) is an exciting new XML-based language for Web graphics from the World Wide Web Consortium (W3C).
http://www.adobe.com/svg/
http://www.adobe.com/svg/demos/samples.html
XML Basics
http://www.ibiblio.org/xml/slides/sd99east/basics/
• XML FAQ:http://www.ucc.ie/xml/
