Multiple device types

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Multiple device types

• Web based services

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Technologies

• XML
• XSL
• ASP
• JSP
• WAP, WML
• Java 2 Micro Edition
• Visual Embedded Toolkits

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Example Systems

• Mobile Information Server - Microsoft
• Cocoon APACHE project vendor neutral

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What is XML

• A meta markup language
• A set of rules for creating semantic tags to
  structure data
• It is made up of Documents, Elements and
  attributes

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Example of an XML Document
ltcoursegt ltslide id 003gt lttitlegtExample of
an XML Documentlt/titlegt ltauthorgt John
Byrnelt/authorgt lt/slidegt lt/coursegt
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Some rules

• XML elements are made up of start and end tags
• e.g. lttitlegtExample of an XML Documentlt/titlegt
• An element can contain one or more attributes.
  These are name value pairs
• e.g.an attribute of the slide element is id
  003
• All elements must have an end tag
• All elements must be cleanly nested
• Values are quoted
• Documents have a unique first element

An XML Document is an XML element that can but
might not include nested XML elements
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Data Interchange
XML
XML is the Webs language for data interchange
(HTML for rendering) For example databases from
different vendors may exchange information using
XML
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Building XML Applications

• Step 1 Write a DTD
• A Document Type Definition defines
• the tags that can exist in your document.
• The sequence of the tags
• The attributes allowed
• The values associated with attributes

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Example DTD
lt?xml encoding"UTF-8"?gt lt!ELEMENT
address(person)gt lt!ELEMENT person
(name,e-mail)gt lt!ELEMENT name (surname,
first)gt lt!ELEMENT surname (PCDATA)gt lt!ELEMENT
first (PCDATA)gt lt!ELEMENT email (PCDATA)gt
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About the sample

• This DTD says that our address is composed of
  one or more people, where each person has a name,
  and optional e-mail address.
• The name is composed of a surname name, and a
  first name. And the content of each of these is
  UTF-8 string data.

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The XML Document

• Step 2 is the production of a document
• The Document is generated by filling in the
  template described by the DTD with appropriate
  values
• The values for elements may various sources
  including database queries

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Interpreting Documents

• Step 3 Application Programmers Interfaces
  (APIs) can be Used to manipulate XML Documents
• Two such APIs exist
• The DOM (Document Object Model)
• The SAX (Simple API for XML)

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Displaying XML

• Your browser can display XML ?
• If not then transform the XML into something your
  browser can display (such as HTML) XSL
  Stylesheets can do this

Result
XML
XSL


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Basic syntax of XML

• In XML, your tags must be properly nested
• In XML, standalone tags, called empty tags, must
  have a trailing slash before the closing
  angle-bracket.
• An XML document must have a single root element,
  which surrounds all others.
• In XML, attribute values must be quoted.
• XML markup tags are case sensitive.
• Whitespace is relevant between start and end
  tags.
• XML is extensible and uses a Document Type
  Declaration (DTD) to define the allowable grammar
  rules for tags and attributes.

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XSL introduction

• Extensible Stylesheet Language
• Has 2 parts
• Formatting Objects
• Transformation Rules (XSLT bit!)
• It provides a presentation language for documents

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XSLT

• For tranforming XML to different targets use the
  XSL
• Transformations
• It can operate independently of XSL it can
  create
• transformations without the use of the
  formatting
• objects

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XSL Processor
Link to stylesheet
XML file
HTML or (depends on Stylesheet used.
HTML or WML or .
XSL file
Result
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Sample Stylesheet file extension .xsl
ltxslstylesheet xmlnsxsl "http//www.w3.org/1999
/XSL/Transform" version"1.0"gt
ltxsloutput method"html"/gt ltxsltemplate
match"/"gt lthtmlgt ltxslapply-templates
select"//book"/gt lt/xsltemplategt ltxsltemplate
match"book"gt This will appear in the result.
lt/xsltemplategt
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XML files Located on server
Tomcat Servlet engine
Cocoon Handles XML
Servlets can use the Cocoon Parser and
manipulate XML documents
Browser requests UML file
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Using IIS
xml
Server
xsl
Multiple devices (HTML WML)
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If ( InStr(testmime,"wml"))Then
xmlDocument.load(Server.MapPath("index.xml")) xsl
Document.load(Server.MapPath("/stylesheets/wmlpage
.xsl")) Response.Write(xmlDocument.transformNod
e(xslDocument))
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Else xmlDocument.load(Server.MapPath("/student/ja
b/index.xml")) xslDocument.load(Server.MapPat
h("/student/jab/stylesheets/webpage.xsl"))
Response.Write(xmlDocument.transformNode(xslDocume
nt)) End If
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WAP

• HTTP/HTML adjusted to small devices
• Consists of a network architecture,a protocol
  stack and a Wireless Markup Language (WML)
• For Internet connection a WAP-gateway is required
• Specifications at http//www.wapforum.org

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WAP - INTERNET
WEB SERVER
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WML

• WML based on XML and HTML.
• Not pages of frames, but decks with cards.
• Images WBMP, WAP specific
• Generally all compiled to binary by WAP gateway
  Additional area of potential problems.

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WMLScript

• The WAP Javascript equivalent.
• Located in separate files
• Also compiled by WAP gateway
• Allows automation of WML and phone functions.