XML Technology in ECommerce

1
XML Technology in E-Commerce

• Lecture 1
• WWW, HTML, CSS, XML, Meta-modeling

2
Lecture Outline

• World Wide Web - facts, architecture
• HTML
• CSS
• XML
• Markups
• Well-formedness
• Meta-modeling

3
World Wide Web

• WWW
• Global hypertext project at CERN
• Proposed by Tim Berners-Lee in 1989
• Web Consortium (W3C) - www.w3.org
• Founded in 1994
• Three hosts - MIT, INRIA, Keio University
• Leads the evolution of the Web
• More than 20 web-related specifications

4
World Wide WebArchitecture
HTTP request for Web Resource
Web Browser
Web Server
HTTP response - usually a Web page

• HTTP - Hypertext Transport Protocol
• HTML - Hypertext Markup Language
• URI - Uniform Resource Identifier - a naming
  scheme for resources on the Web

5
HTMLExample
lthtmlgt ltheadgt lttitlegt XML Technology in
E-Commercelt/titlegt lt/headgt ltbodygt
lth1gtLecture 1lt/h1gt ltpgt Example of HTMLlt/Pgt
ltpgt Resources lta hrefhttp//www.w3.orggt W3C
lt/agt Web Consortiumlt/pgt lt/bodygt lt/htmlgt
Other Examples - Deitel 2.4, page 26 3.2, page
47
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HTMLForms

• Enable development of web applications - user
  interface is presented by the browser
• Web server handles form data through server
  extensions
• Opens a possibility for dynamic web pages
• CGI (Common Gateway Interface) - protocol for
  data exchange between the server and its
  extensions (CGI scripts)
• Popular languages for CGI programming - Perl, C,
  Python, Java, VBScript, JavaScript

Examples - Deitel 3.4, page 52
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HTMLLinks
Web Resource
Web page

• Link has two ends (anchors) and direction
• A element - sets up an anchor
• lta hrefhttp//java.sun.comgtJava Homelt/agt sets
  up a source anchor. href attribute contains an
  URI
• lta namedestgt TOC lt/agt - sets up a destination
  anchor
• Link behavior - destination resource is retrieved
  and displayed

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HTMLltmetagt tags usage

• Meta data about the document
• ltmeta nameauthor contentJohn Smithgt
• ltmeta nameaddress contentan addressgt
• HTTP response headers
• ltmeta http-equivrefresh content1000
  http//www.foo.comgt
• Data for search agents
• ltmeta namekeywords contentXML, WEBgt

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HTMLMultimedia, extra functionality, editors

• Multimedia content - plug-in and ActiveX
  technology
• Scripts - dynamic and interactive web pages on
  the client side
• Java Applets - programs executed in the browser
  environment
• HTML editors - FrontPage, Dreamweaver, NetObjects
  Fusion, Adobe GoLive
• Demo Editing web pages with FrontPage

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CSSCascading Style Sheets

• Purpose - specify the layout of web pages
• Benefits
• Separate structure from presentation
• Impose consistent look and feel to the entire
  site
• Promotes reusability
• Specifications
• CSS level 1 and 2
• CSS level 3 - work in progress

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CSSDeclaration

• Inline styles
• ltp stylefont-size 20 pt color bluegt some
  text lt/pgt
• style element
• ltstyle typetext/cssgt
• p font-size 20pt color blue
• lt/stylegt
• External style sheets
• ltheadgt
• ltlink relstylesheet typetext/css
  hrefaStyle.cssgt
• lt/headgt

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CSSCascading and Inheritance

• Style origin
• User agent (browser) default style sheet
• User style
• Author style
• Cascading order - how to resolve conflicts
  between style rules
• Inheritance - an element inherits style
  properties from its ancestors

More info - Deitel 4.4, page 84
13
XMLXML, HTML, SGML

• HTML Drawbacks
• Fixed Tags Set
• Poor Linking
• Does not support validation
• Simple structures
• Specifies only presentation

Relations between SGML, HTML and XML
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XMLIdea
ltaddressgt
Sherlock Holmes
ltnamegt
lt/namegt
Baker Street 221b
ltstreetgt
lt/streetgt
London
ltcitygt
lt/citygt
England
ltcountrygt
lt/countrygt
lt/addressgt
15
XMLBasic terms
Annotated XML Specification http//www.xml.com/ax
ml/testaxml.htm
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XMLCharacters and Markups

• Characters in the XML document form markups and
  character data
• Markups
• start, end and empty element tags
• entity and character references
• comments
• CDATA delimiters
• Document type declarations
• Processing Instructions
• All other characters form character data

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XMLElements and elements content

• ltname attr1value1 gt..Content..lt/namegt

Elements content
Attribute specification
End tag
Start tag
ltimg srcanImage.gif /gt - Empty element

• Elements content
• Only elements
• Empty
• Mixed (character data and other elements)

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XMLExample

• ltperson age45gt
• ltnamegtSherlock Holmeslt/namegt
• ltaddressgt
• ltstreetgtBaker Street 221blt/streetgt
• ltzipgt1111lt/zipgt
• ltcitygtLondonlt/citygt
• ltcountrygtEnglandlt/countrygt
• lt/addressgt
• lthomepage hrefhttp//www.sherlock-holmes.co.u
  k//gt
• ltnotegtltemgtSherlock Holmeslt/emgt and ltemgtDoctor
  Watsonlt/emgt lived at 221b Baker Street between
  1881-1904, according to the stories written by
  ltemgtSir Arthur Conan Doylelt/emgt.lt/notegt
• lt/persongt

19
XMLProcessing Instructions and CDATA Sections

• Processing Instructions
• lt?xmlstylesheet type"text/css"
  href"bach.css"?gt
• lt?cocoon-process type"xslt"?gt
• CDATA Sections
• lt!CDATA ltH1gt Hello World! lt/H1gt gt
• lt!CDATA
• if((x0) (y lt2)) System.out.print
  ln(Ok!)
• gt

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XMLNamespaces

• Purpose - resolve name collisions in a single XML
  document
• Definition - Set of names uniquely identified by
  URI, used for element types and attribute names
• Namespace declaration
• lthtmlhtml xmlnshtmlhttp//www.w3.org/TR/REC-ht
  ml40gt
• lthtmlheadgt.lt/htmlheadgt
• lthtmlbodygt.lt/htmlbodygt
• lt/htmlhtmlgt

Examples - Deitel 5.8, page 123
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XML Meta-modelling - well-formedness
EBNF
EBNF
Defines
Defines
Pascal Grammar
XML Grammar
WF Constraints
Defines
Defines
a Pascal Program
an XML Document
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XML Meta-modelling - validity
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XML Tool Support

• Browser support
• Netscape - XML, CSS1, CSS2 (partly)
• IE 5 - XML, CSS1, CSS2 (partly), XSLT
• Opera - XML, CSS1, CSS2(partly)
• XML Editors
• XML Spy 3.5
• XMetal
• Epic
• FrameMaker
• Demo Visualizing XML files in IE5, editing with
  XML Spy

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Summary

• Todays Web - HTTP, URI, HTML, CSS
• XML is a technology for creating markup
  languages
• XML documents contain character data and markups
• Elements are the main building blocks for the
  document structure
• Document well-formedness means conformance to the
  XML grammar and constraints

Read Deitel 1..5, Well-formedness and Validity
of XML Documents Skip Deitel 3.3, 3.5, 3.7, 3.9,
3.10, 4.6 .. 4.10 Assignment Deitel Ex 5.4 and
Ex 5.7, pages 132, 133