eXtensible Markup Language (XML)

eXtensible Markup Language
(XML)

Serhii Kartashov
July 2012
SoftServe
IFDC IT Academy

Agenda
Introduction to XML

Basic rules

Parsing XML

XML Namespaces

XML Schemas

XSLT Transformation

Where is XML applying? (examples)

Origin of XML
SGML
1986

HTML 1.0 XML 1.0
1992 1998

HTML XHTML
4.01 1999 1.0 2000

XHTML
2.0 2010

XML Data Model (a tree)
1 root

2 title item item

name name

company company

3
model model

cost cost

Basic rules
• All XML Elements Must Have a Closing
• XML Tags are Case Sensitive
• XML Elements Must be Properly Nested
• XML Attribute Values Must be Quoted
• XML Documents Must Have a Root Element
• Entity References
• White-space is Preserved in XML

Parsing XML
XML parser -- Reads in XML data, checks for
syntactic constraints, and makes data available
to an application. There are three 'generic'
parser APIs
– SAX Simple API to XML (event-based)
– DOM Document Object Model (object/tree based)

XML Parser Processing Model

parser XML-based
parser
interface application

DOM APIs
DocumentBuilder
Factory Packages:
 org.w3c.dom
 javax.xml.parsers
Document Document (DocumentBuilderFactory,
XML Builder (DOM) DocumentBuilder) READ
 javax.xml.transform
(TransformerFactory, Trans
former, Source, Result)
WRITE
Transformer
Factory

Document Transformer
(DOM) XML

SAX APIs
Packages:
 org.xml.sax
 org.xml.sax.ext
 org.xml.sax.helpers
 javax.xml.parsers
(SAXParserFactory, SAXParse
r)

Why namespaces?
HTML:
<table>
<tr>
<td>Apples</td>
<td>Bananas</td>
</tr> We have the conflict
</table> between two elements
(table). And parser
XML: doesn’t know how
<table> handle this situation.
<name>African Coffee Table</name>
<width>80</width>
<length>120</length>
</table>

Namespaces handle conflicts between
element names.
HTML:
<h:table xmlns:h="http://www.mysite.org/html>
<h:tr>
<h:td>Apples</h:td>
<h:td>Bananas</h:td> We added name prefix to
</h:tr> each element (table). And
</h:table> declared they.

XML:
<x:table xmlns:x="http://www.mysite.org/xml>
<x:name>African Coffee Table</x:name>
<x:width>80</x:width>
<x:length>120</x:length>
</x:table>

Defining language dialects
• Two ways of doing so:
– XML Document Type Declaration (DTD)– Part of core XML
spec.
– XML Schema – allows for stronger constraints on XML
documents.

• Adding dialect specifications implies two classes of
XML data:
– Well-formed An XML document that is syntactically
correct
– Valid An XML document that is both well-formed and
consistent with a specific DTD (or Schema)

DTD
<!ELEMENT root (title?, item*)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT item (name, company, model, cost)>
<!ATTRIBUTE id (#PCDATA)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT company (#PCDATA)>
<!ELEMENT model (#PCDATA)>
<!ELEMENT cost (#PCDATA)>

XML Schema
<?xml version="1.0" encoding="ISO-8859-1" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name=“root">
<xs:complexType>
<xs:sequence>
<xs:element name=“title" type="xs:string"/>
<xs:element name=“item“ maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name=“name" type="xs:string"/>
<xs:element name=“company" type="xs:string"/>
<xs:element name="model" type="xs:string"/>
<xs:element name="cost" type="xs:decimal"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name=“id" type="xs:positiveInteger " use="required"/>
</xs:complexType>
</xs:element>

</xs:schema>

XML Parser Processing Model With
Validation Schema

parser XML-based
parser
interface application

XML
Schema

XSLT Transformation
XSLT (EXtensible Stylesheet Language
Transformation):
• <template>
• <value-of>
• <for-each>
• <sort>
• <if>
• <choose>

XML file
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="class.xsl"?>
<class>
<student>Jack</student>
<student>Harry</student>
<student>Rebecca</student>
<teacher>Mr. Bean</teacher>
</class>

XSL file
<?xml version="1.0" ?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="teacher">
<p><u><xsl:value-of select="."/></u></p>
</xsl:template>

<xsl:template match="student">
<p><b><xsl:value-of select="."/></b></p>
</xsl:template>
<xsl:template match="/">
<html>
<body>
<xsl:apply-templates/>
</body>
</html>
</xsl:template>

</xsl:stylesheet>

Web Design and Applications
• XML and CSS (example)
@CHARSET "UTF-8";
title{
display: block;
text-align: center;
font-style: italic;
}
item:after{
font-size: 250%;
content: attr(id);
}
item{
display: block;
padding:20px;
border-style: solid;
font-size: 12px;
}

XML Technology
• XML Transformation
• XML Schema
• XSLT (eXtensible Stylesheet Language
Transformations)
• MathML (Mathematical Markup Language)

Web of Services
• HTTP (HyperText Transfer Protocol)
• SOAP (Simple Object Access Protocol)
• WSDL (Web Services Description Language)

Web of Devices
• Mobile Web
• VXML (Voice XML)

Browsers and Authoring Tools
• Social networks
• Forums
• CMSs (Content Management System)
• RSS (Really Simple Syndication)

Useful links
• Introduction to XML
– http://www.itwriting.com/xmlintro.php
– The development history http://www.w3.org/XML/hist2002
• Basic rules
– http://www.w3.org/TR/2006/REC-xml11-20060816/
• XML Namespaces
– http://www.w3.org/TR/REC-xml-names/
• Defining language dialects
– http://www.w3.org/TR/xhtml1/dtds.html
– http://www.w3.org/TR/xmlschema-0/
• Parsing XML
– http://www.w3.org/DOM/DOMTR
• XSLT Transformation
– http://www.w3.org/TR/xslt

Contacts

• http://it-academy-sk.blogspot.com/

Thank you!

eXtensible Markup Language (XML)

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