XML in the Mozilla Architecture

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XML in the Mozilla Architecture
Shalabh Chaturvedi Persistent Systems Pvt
Ltd Pune shalabh_at_pspl.co.in
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Outline

• What is Mozilla?
• XUL (XML Based User Interface Language)
• RDF (Resource Description Format)
• XUL Templates - Mixing XUL and RDF
• Possibilities

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Mozilla Story
1998
1999
2000
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Mozilla Design

• Front end or Chrome
• drawn using GUI toolkits
• platform specific

• Web page
• drawn by a layout engine

A web browser
Bitter truth maintaining front ends on multiple
platforms is painful

• What if
• Code could be written only once?
• Creating GUIs could be as simple as web pages?
• The layout engine also rendered the chrome?

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What is XUL ?
Specification for the user interface
gecko
The layout engine
A Graphical User Interface
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XUL Elements
ltmenubargt, ltmenugt, ltmenupopupgt, ltmenuitemgt
lttabcontrolgt, lttabgt, lttabpanelgt, lttabboxgt
(many more)

• Elements exist for all common UI widgets
• Look and feel can be changed using CSS
• Not yet a W3C Specification

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RDF
Resource Description Framework

• Defines a data model for describing resources
• Suited to particular kind of information
• Data Model
• Resources
• Properties
• Statements
• XML Serialization Syntax

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RDF Data Model
Three statements about a resource Tintin
Tintin
colourOfHair
hasPet
brown
Snowy
hasFriends
rdftype
rdfseq
Capt Haddock
Prof Calculus
Thomson
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Combining XUL and RDF
RDF in Mozilla

• RDF datasource collection of RDF statements
• Within mozilla all data is represented as RDF
  datasources

XUL

• Defines the user interface

XUL Templates

• Pull data from RDF datasources into XUL elements
• Generate XUL elements dynamically

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The Big Picture
Datasource (collection of rdf statements)
XUL (with templates)
mozilla
Dynamic Content
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XUL Templates
Template
Content produced

• A
• lttemplategt
• ltrulegt
• ltconditionsgt
• ltactiongt
• B
• C uri?x
• D

• A
• B
• C (1)
• C (2)
• C (3)
• D

Note A, B, C and D are XUL elements
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XUL Template Example
ltmenu datasources"tintin.rdf"
ref"urntintin"gt lttemplategt ltrulegt
ltconditionsgt ltcontent uri"?uri"
/gt lttriple subject"?uri"
predicate"http//my.homepage.com/tintinha
sFriends" object"?friends" /gt
ltmember container"?friends"
child"?friend" /gt lttriple
subject"?friend"
predicate"http//my.homepage.com/tintinname"
object"?name" /gt
lt/conditionsgt ltactiongt
ltmenupopupgt ltmenuitem
uri"?friend" value"?name" /gt
lt/menupopupgt lt/actiongt lt/rulegt
lt/templategt lt/menugt
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Possibilities

• Cross platform distributed applications
• The big XML advantage - interoperability
• Examples existing today
• Mozilla web browser, mail client, editor
• XMLTerm (terminal)
• MozInvaders (space invaders game)
• ZopeStudio (management console)
• many more...

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References

• Mozilla and applications
• http//www.mozilla.org/
• http//dmoz.org/ (search for XUL)
• http//www.mozdev.org/
• XUL
• http//www.mozilla.org/docs/
• http//www.mozilla.org/xpfe/xulref/
• RDF
• http//www.w3.org/RDF/
• http//www.mozilla.org/rdf/doc/
• http//entwickler.com/mozine/doc/rdf-slides/

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RDF-XML Example
lt?xml version"1.0"?gt ltrdfRDF
xmlnsrdf"http//www.w3.org/1999/02/22-rdf-syntax
-ns" xmlnsmy"http//my.homepage.com/tintin
gt ltrdfDescription about"urntintin"gt
ltmyhasFriendsgt ltrdfSeqgt
ltrdfligtltrdfDescription mynameCapt Haddock"
/gtlt/rdfligt ltrdfligtltrdfDescription
mynameThomson" /gtlt/rdfligt
ltrdfligtltrdfDescription mynameProf Calculus"
/gtlt/rdfligt lt/rdfSeqgt
lt/nchasFriendsgt lt/rdfDescriptiongt lt/rdfRDFgt
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More about XUL

• Easy and fast development
• Scriptable using DOM
• Overlays
• Templates for dynamic content
• XBL for extensibility
• Cross platform