XML DEMYSTIFIED
Presented By Carl-Erik Svensson
Announcements
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Assignment 1.2 is due Wednesday 2/11/09 at 8am
Name your SVN check-in mp1.2
 csil-projects.cs.uiuc.edu/svn/sp09/cs242/netid/mp1.2
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Make sure you are attending discussion
 Make sure you are using SVN
 Assignment 1.3 is due Wednesday 2/18/09 at 8am
 My office hours on 2/16/09 will be cancelled
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WHAT THE!?
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Extensible Markup Language
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A nested tree structure of elements
Allows users to define their own elements
 Designed for carrying data
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SIGNIFICANCE
Creates an open standard for sharing data
 Simple, and easy to read both by people and
machines
 Foundation for many Internet languages
 Separates content from presentation
 Widely adopted
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Microsoft, IBM, Sun, SAP, Mozilla, …
ARE YOU FOR SERIOUS?
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Here’s a list of technologies/products that use
XML
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Open XML (ala .docx files and Office 2007)
Google Earth (KML)
Finale Notepad (MusicXML)
Scalar Vector Graphics (SVG)
The Internet (HTML)
Really Simple Syndication Feeds (RSS)
Apache ANT
A BRIEF HISTORY
Evolved from SGML (1986), inspired by Charles
Goldfarb (and co.) at IBM in 1970
 Resulted in HTML
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Standards were loosened
 Data and display became intertwined (bad!)
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Adopted by Microsoft, Sun, and IBM
Useful for interoperability
 Owned by W3C
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STRUCTURE
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XML has a tree structure
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Contains a root element
Beneath the root are additional elements
 Each element can have various attributes
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It is implemented with tags
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<aTag> contains text or other tags
Every opening <tag> must contain a closing </tag>
Tags can have any name
EXAMPLE
EXAMPLE…
Root Element
Attribute
Value
VALIDATION
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We want to share our data with the world
The world needs to know what our data looks like
 We can define our data with a schema
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XML Data can then be validated automatically
XSD
 DTD
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XPATH
A method of traversing an XML document
 Useful for retrieving attributes and values of tags
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DTD
DISPLAY
We have data, now what?
 This data can be parsed by any number of
programs
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Data generated by web scraping
 Kernel files consumed by image convolution
 DEM to BMP converters/manipulators
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We can also display the data directly
CSS
 XSL(T)
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CSS
XSLT
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A method of defining a transformation from XML
to something else
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Usually HTML
Contains complex structure
Can define rules for each tag
 Typically these rules describe how to render a tag
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Utilizes XPath expressions
Assignment 1.3
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Use an XML file to define operations
This will require parsing an XML file
 Luckily, there are some parsers we can use
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Call operations defined in the XML file
Now we can define any combinations of basic
operations as a single operation
 This makes our application externally programmable
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Due Wednesday, Feb 18th at 8am in SVN
Assignment 1.3 - Sample XML
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Root is Operations
Operations contains
multiple ComplexOps
Each ComplexOp is named
and contains multiple Ops
Each Op is named and
contains parameters
Assignment 1.3 - DTD
RESOURCES
http://www.w3schools.com/xml/default.asp
 http://www.itwriting.com/xmlintro.php
 http://www.w3schools.com/xpath/default.asp
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http://www.w3schools.com/DTD/
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http://www.grinninglizard.com/tinyxml/
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http://ezxml.sourceforge.net/
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http://agora.cs.illinois.edu/display/cs242sp09/Assignment+1.3