XML and XSLT

XML and XSL
Institutional Web Management 2001:
Organising Chaos

Running order
Background
All about XML
All about XSL
Hands-on XML and XSL
Publishing engines
Example applications
Crystal balls

Background
Mark Ray and Andrew Savory
Using XML since 1996
Used a variety of tools and methods

XML and XSL
W3C specifications
Separation of Concerns
Reuse of data
Multiple output formats
Styles tailored to reader / Standardised styles

Applications of XML and XSL
Static information
Institutional web sites
Prospectuses
Course catalogues
Dynamic information
News or event information services
Course catalogues
Staff directories

Benefits of XML and XSL
Standards-based, format-independent
Serve sites and formats based on user need
Text-based (text readers, slow links, low-tech)
Netscape / Internet Explorer specifc
TV, Phone, PDA
PDF, SVG, VRML, ...
Simplification of web site management...

The management bit
Management
Decide what the site should contain, how it should behave and how it should appear
Content
Responsible for writing, owning, managing the site content

The management bit
Logic
Responsible for integration with dynamic content generation
Style
Responsible for information presentation, look & feel, site graphics and maintenance

What is XML?
eXtensible Markup Language
Not a fixed format
'Metalanguage'
For describing information

XML Design Goals
XML shall be straightforwardly usable over the Internet.
XML shall support a wide variety of applications.
XML shall be compatible with SGML.
It shall be easy to write programs which process XML documents.
The number of optional features in XML is to be kept to the absolute minimum, ideally zero.

XML Design Goals
XML documents should be human-legible and reasonably clear.
The XML design should be prepared quickly.
The design of XML shall be formal and concise.
XML documents shall be easy to create.
Terseness is of minimal importance.

Structure of an XML document
<?xml version="1.0"?>
<PARENT>
<CHILD>
This is content.
</CHILD>
<EMPTY/>
</PARENT>

A first XML document
Construct a well-formed XML document using the following tags:
xml opening tag
page
title
content
para
Don't forget to add the closing tags!

Differences to HTML
Order:
<tag1><tag2></tag1></tag2> WRONG
<tag1><tag2></tag2></tag1> RIGHT
Balance
<tag1><tag2></tag2> WRONG
Case
<tag1><tag2></TAG2></TAG1> WRONG

Differences to HTML
Attributes
<tag1 class=wrong> WRONG
<tag1 class="right"> RIGHT
Empty Tags
<tag1 class="wrong"> WRONG
<tag1 class="wrong" /> RIGHT
XML is stricter
...and therefore better!

Well-formed vs. Valid
Exactly what they say:
Well-formed means it's written correctly
Valid means we can validate it

A well-formed example
<PARENT>
<CHILD>
<MARK NUMBER="1" LISTED="yes" TYPE="natural"/>
<NAME>
<LASTNAME>child</LASTNAME>
<FIRSTNAME>second</FIRSTNAME>
</NAME>
</CHILD>
</PARENT>

A valid example
<!DOCTYPE PARENT [
<!ELEMENT PARENT (CHILD*)>
<!ELEMENT CHILD (MARK?,NAME+)>
<!ELEMENT MARK EMPTY>
<!ELEMENT NAME (LASTNAME+,FIRSTNAME+)*>
<!ELEMENT LASTNAME (#PCDATA)>
<!ELEMENT FIRSTNAME (#PCDATA)>
<!ATTLIST MARK
NUMBER ID #REQUIRED
LISTED CDATA #FIXED "yes"
TYPE (natural|adopted) "natural">
<!ENTITY STATEMENT "This is well-formed XML">
]>
<PARENT>
&STATEMENT;
<CHILD>
<MARK NUMBER="1" LISTED="yes" TYPE="natural"/>
<NAME>
<LASTNAME>child</LASTNAME>
<FIRSTNAME>second</FIRSTNAME>
</NAME>
</CHILD>
</PARENT>

Document Type Definitions
First standard mechanism for XML validation
Define the role and structure of XML elements
Sufficient for simple XML schemas
Don't support namespaces
Use non-XML syntax

XSchema
XML structural definition language of choice
Defines a class of XML document
Supports name spaces
More powerful

Xschema example
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:annotation>
<xsd:documentation xml:lang="en">
Example Schema for IWM workshop
</xsd:documentation>
</xsd:annotation>
<xsd:element name="page" type="page"/>
<xsd:complexType name="page">
<xsd:sequence>
<xsd:element name="title" type="xsd:string"/>
<xsd:element name="content" type="pageContent"/>
</xsd:sequence>
</xsd:complexType>
<xsd:complexType name="pageContent">
<xsd:sequence>
<xsd:element name="para" type="xsd:string" minOccurs="0"/>
</xsd:sequence>
</xsd:complexType>
</xsd:schema>

What is XSL?
Preferred style sheet language of XML
a method for transforming XML documents
a method for defining XML parts and patterns
a method for formatting XML documents
An application of XML (same formatting rules)

Hands-on XML
Create the following XML document:
<page>
<title>Hello</title>
<content>
<para>This is my first XML page!</para>
</content>
</page>
Save it as hello_world.xml

Uploading the file
Navigate to the site provided
Click on "upload.html"
Beside the "file to upload" box, click on "choose"
Select the file you want to upload
Click on "upload"

Viewing the file
If you see the file you wanted to upload and receive a "File written successfully" message...
Click on "Content", then the name of the file

Structure of an XSL stylesheet
Most templates have the following form:
<xsl:template match="emphasis">
<i><xsl:apply-templates/></i>
</xsl:template>
The whole <xsl:template> element is a template
The match pattern determines where this template applies

Structure of an XSL stylesheet
Literal result element(s) come from non-XSL namespace(s)
XSLT elements come from the XSL namespace

Hands-on XSL
Create the following XSL stylesheet:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="page">
<html>
<head>
<title><xsl:value-of select="title"/></title>
</head>
<body bgcolor="white" alink="red" link="blue" vlink="blue">
<xsl:apply-templates/>
</body>
</html>
</xsl:template>
</xsl:stylesheet>

Uploading the file
Click on "upload"

Publishing engines
Cocoon
Java-based
AxKit
Perl-based
4Suite
Python
Others or roll your own

Viewing the file
Click on "View site in cocoon"
Select the file you uploaded and the stylesheet you want to view it in

Hands-on XSL
Add the following to the XSL stylesheet:
<xsl:template match="title">
<h2 style="color: navy; text-align: center">
<xsl:apply-templates/>
</h2>
</xsl:template>
<xsl:template match="para">
<p align="left">
<i><xsl:apply-templates/></i>
</p>
</xsl:template>

New platforms, new beginnings?
The old way of publishing
Repurposing
The new way of publishing
Target multiple platforms
Multiple stylesheets
Multiple formats

Browser-specific content
<map:select>
<map:when test="lynx">
<map:transform src="stylesheets/simple-page2html-lynx.xsl"/>
</map:when>
<map:otherwise>
<map:transform src="stylesheets/simple-page2html.xsl"/>
</map:otherwise>
</map:select>

Lynx-friendly XSL stylesheet
Add the following to your XSL stylesheet:
<h2>This site is lynx-friendly</h2>
Save the stylesheet as
simple-page2html-lynx.xsl

Uploading the file
Click on "upload"

Viewing the file
Click on "View site in cocoon"
Select the file you uploaded and the stylesheet you want to view it in

Where next?
The semantic web

References
http://www.ibm.com/developerworks/papers.nsf/dw/xml-papers-bytopic?OpenDocument&Count=500
http://www.xml101.com/
http://nwalsh.com/docs/tutorials/xsl/

XML and XSLT

by Andrew Savory on Jun 15, 2010

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XML and XSLT — Presentation Transcript