XMLRealizing Portable Data

Ryan WilsonFebruary 12, 2003

XML Agenda

<?xml version=“1.0”?>

<presentation>

<agenda>

<item>The Problem of Data</item>

<item>What is XML?</item>

<item>Extensions of XML</item>

<item>Practical Applications</item>

</agenda>

</presentation>

The Problem of Data

How do you store or send data in your application?

Document Storage ex. Word, Excel, HTML, etc.

Configuration Files Remote Procedure Calls

The Problem of Data

Proprietary formats Reinventing the wheel

Rewrite (and debug) parsers Document format for others

What is XML?

Extensible Markup Language Derived from SGML

W3C Standard (1998) A standard format for all types of

computer documents Human readable format

Always text, never binary data

What is XML?

Data is strings of text and delimited by tags

XML doesn’t define the tags! Makes it a meta-markup language Flexibility

XML does define what the tags look like and how they can be organized

What is XML?

<?xml version=“1.0”?>

<!-- class information data -->

<classRoster course=“COT4810” section=“2”>

<teacher>Dutton</teacher>

<student>Wilson</student>

<student>Doe</student>

<testdate></testdate>

<testdate/>

</classRoster>

Tags

<?xml version=“1.0”?>

<!-- class information data -->

<classRoster course=“COT4810” section=“2”>

<teacher>Dutton</teacher>

<student>Wilson</student>

<student>Doe</student>

<testdate></testdate>

<testdate/>

</classRoster>

Start Tags

<?xml version=“1.0”?>

<!-- class information data -->

<classRoster course=“COT4810” section=“2”><teacher>Dutton</teacher><student>Wilson</student><student>Doe</student><testdate></testdate>

<testdate/></classRoster>

End Tags

<?xml version=“1.0”?>

<!-- class information data -->

<classRoster course=“COT4810” section=“2”>

<teacher>Dutton</teacher>

<student>Wilson</student>

<student>Doe</student>

<testdate></testdate>

<testdate/>

</classRoster>

Attributes

<?xml version=“1.0”?>

<!-- class information data -->

<classRoster course=“COT4810” section=“2”><teacher>Dutton</teacher>

<student>Wilson</student>

<student>Doe</student>

<testdate></testdate>

<testdate/>

</classRoster>

Processing Instructions

<?xml version=“1.0”?><!-- class information data -->

<classRoster course=“COT4810” section=“2”>

<teacher>Dutton</teacher>

<student>Wilson</student>

<student>Doe</student>

<testdate></testdate>

<testdate/>

</classRoster>

Comments

<?xml version=“1.0”?>

<!-- class information data --><classRoster course=“COT4810” section=“2”>

<teacher>Dutton</teacher>

<student>Wilson</student>

<student>Doe</student>

<testdate></testdate>

<testdate/>

</classRoster>

What is XML?

You define the tags to use XML Application

XML Application “Grammar” can be formally defined in: DTD (Document Type Definition) XML Schema

What can XML do?

Document Storage ex. Open Office

Books/Technical Documents Remote Procedure Calls Vector Graphics Slices, Dices, and makes Julian Fries!

What XML is Not Programming Language

Doesn’t do anything Network-Transport Protocol “XML is a structural and semantic

markup language, not a presentation language”(XML in a Nutshell p.4)

Not like HTML Database

XML can be stored in a database Database could save its data in XML

XML – Portable Data

Simple Well-documented Human-readable ex. NASA’s moon landings data

Using XML Lots of XML parsers available

Don’t have to write your own! Standards for Parsers

DOM – Document Object Model Creates XML Tree Reads in whole document before

processing Read/Write

SAX Processes XML as it is read Read-only

DOM – XML Tree<student> <name>Ryan Wilson</name> <major>Computer Science</major></student>

Root

student

Ryan Wilson

majorname

Computer Science

Extensions to XML

XSLT Extensible Stylesheet Language

Transformations Convert an XML document into

another document ex. XML document into a web

page

<book title=“LoTR: The Two Towers”>

<chapter title=“The Departure of Boromir”>

Aragorn sped up the hill…

</chapter>

<chapter title=“The Riders of Rohan”>

Dusk deepened. Mist lay behind them…

</chapter>

<chapter title=“The Uruk-Hai”>

Pippin lay in a dark and troubled dream…

</chapter>

</book>

<html>

<head>

<title>LoTR: The Two Towers</title>

</head>

<body>

<h1>Table of Contents</h1>

<ol>

<li>The Departure of Boromir</li>

<li>The Riders of Rohan</li>

<li>The Uruk-Hai</li>

</ol>

</body>

</html>

Extensions to XML

Presentation XML or “Making your XML Look Pretty”

CSSCascading Style Sheets Already used for web pages Describes how to display XML

XSL-FOXSL Formatting Objects Use XSLT to turn into XSL-FO

Practical Applicationsor “Why CS Students should care about XML”

Web publishing frameworks www.gentoo.org ex. Apache’s Cocoon

Configuration Files ex. Gconf

Remote Procedure Calls (RPC) XML-RPC SOAP –

Simple Object Access Protocol

For More Information

www.xml.com O’Reilly Books

XML in a Nutshell Java and XML

xml.apache.org

Questions?