An XML Introduction

1
An XML Introduction

• Next Generation Web Data
• Ian GRAHAM
• Centre for Academic Technology
• Tel [phone]
• Email
• Talk http//www.utoronto.ca/ian/talks/

2
Overview

• An XML example
• -- so whats so special about XML?
• The birth of the Web -- HTML
• HTML is not enough -- why?
• XML for universal data
• Common uses and applications

3
XML Example test.xml

• Title of text XHTML Document
• Heading of Page
• here is a paragraph of text. I will
  include inside this paragraph a bunch of
• wonky text so that it looks fancy.
  
• Here is another paragraph with
  inline emphasized text, and
• absolutely no sense of humor.
  
• And here is another paragraph, this one
  containing an
• alt"waste of time" / inline image,
  and a
  line break.

4
What do browsers do?

• Netscape 5 -- ignores the tags ... or so it seems
  ...
• Internet Explorer 5 -- shows a tree of elements.

5
The Birth of the Web

• The HyperText Markup Language
• A simple language for distributing text
• All that other stuff
• URLs, HTTP, CGI ...

6
HTML Evolution

• Started with very few tags
• Language evolved, as more tags were added
• forms
• tables
• fonts
• frames

7
HTML Problems

• Desire for personalized tags
• Want to put data into HTML form
• mathematics, database entries, literary text,
  poems, purchase orders .
• HTML just isnt designed for that!

8
HTML Problems (2)

• Software processing
• Server management of data
• But -- HTML is so ill-formed, this is hard!

HTML
HTML
HTML
HTML
HTML
9
Idea Back to the Basics

• HTML was defined using SGML
• Standard Generalized Markup Language
• A meta-language for defining languages.
• Complex, sophisticated, powerful
• Idea Use SGML

10
Languages based on SGML
HTML
TEI
DocBook
. . .
SGML
11
Problems with SGML

• Too complicated a language
• Rules are too strict
• Not good in a distributed environment
• Cant mix different data together

12
Idea (2) Webified SGML

• New eXtensible Markup Language XML
• Can use XML to define new languages
• Distributes easily on the Web
• Can mix different types of data together

13
Basic XML Rules

• Tags like in HTML, but ...
• Technical details
• Always need end tags
• Special empty-element tags
• Always quote attribute values

14
Like this example ..
xmlns"http//www.w3.org/TR/xhtml1"
Title of text XHTML Document

Heading of Page .. And
here is another paragraph, this one containing
an of time" / inline image, and a
/ line break.
15
Evolution of XML

• Many XML languages, optimised for different roles
• MathML -- for mathematics
• SMIL -- for synchronised multimedia
• RDF -- for describing things
• XUL -- for describing the Navigator 5 user
  interface

16
MathML

• Designed to express semantics of maths
• Also can express layout
• Cut paste into Maple, Mathematica

• x2 4x 4 0
• x 2
  
• 4
• invisibletimes
• x
• 4
• 0

17
SMIL

• Synchronised Multimedia Integration Language
• Integration of multimedia with text, audio, video
• Support in RealPlayer G2

18
SMIL Example
content"Online Teaching Services promo" /


background-color"white"/ id"AnimChannel1" title"AnimChannel1"
left"0" top"0" height"265" width"280"
fit"hidden"/ title"Online Teaching Services promo"
author"Jay Moonah, CAT" src"final.rm" id"Soundtrack"
title"Soundtrack"/ src"otscompfin.swf" id"Animation"
region"AnimChannel1" title"Animation"
fill"freeze"/ id"caption" region"cc" title"cc"
fill"freeze"/
19
XHTML NextGen HTML

• Title of text XHTML Document
• Heading of Page
• here is a paragraph of text. I will
  include inside this paragraph
• a bunch of wonky text so that it
  looks fancy.
• Here is another paragraph with
  inline emphasized
• text, and absolutely no sense
  of humor.
• And another paragraph, this one with an
  
• alt"waste of time" / image, and a
  
  line break.

20
XHTML

• Just like HTML, but based on XML rules
• Will support integration of different data into a
  single document

21
XHTML and other Data

• Title of XHTML Document
• Heading of Page
• MathML markup
• more html stuff goes here
• SMIL markup

22
Other Use Data Abstraction

• XML as a universal format for data interchange
• Machines exchange data as XML-format messages
• Eliminates proprietary data formats
• Lots of XML processing software available

23
XML Messaging
24
XML Messaging
Other DB
Request/send data
Database
Other DB
Other DB
Request/send data
25
Example Message

• .desc
• 23h
• Gold sprockel grommets, with
  matching hamster
• 12
• 423h
• . Order something else ..

26
The XML Family Tree
HTML
TEI
. . .
. . .
XML
SGML
27
Other Examples

• XUL XML User Interface Language
• How Navigator 5 configures its interface
• RDF Resource Description Framework
• For describing things
• Used by Netscape Open Catalog project to define
  Web accessible resources

28
Summary

• a framework for distributing data on the Web
• an integration tool for mixing different types of
  data
• a universal format for exchanging data between
  machines

29
An XML Introduction

• Next Generation Web Data
• Ian GRAHAM
• Centre for Academic Technology
• Tel [phone]
• Email
• Talk http//www.utoronto.ca/ian/talks/