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

1 XML shall be straightforwardly usable over the Internet.

2 XML shall support a wide variety of applications.

3 XML shall be compatible with SGML.

4 It shall be easy to write programs which process XML documents.

5 The number of optional features in XML is to be kept to the absolute minimum, ideally zero.

XML Design Goals

6 XML documents should be human-legible and reasonably clear.

7 The XML design should be prepared quickly.

8 The design of XML shall be formal and concise.

9 XML documents shall be easy to create.

10Terseness 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

<tag1><tag2></tag2></tag1> RIGHT

Case<tag1><tag2></TAG2></TAG1> WRONG

<tag1><tag2></tag2></tag1> RIGHT

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

<?xml version="1.0"?>

<PARENT><CHILD>

<MARK NUMBER="1" LISTED="yes" TYPE="natural"/>

<NAME>

<LASTNAME>child</LASTNAME>

<FIRSTNAME>second</FIRSTNAME>

</NAME>

</CHILD>

</PARENT>

A valid example

<?xml version="1.0"?><!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 #REQUIREDLISTED 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

<?xml version="1.0"?>

<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:

<?xml version="1.0"?>

<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:<?xml version="1.0"?>

<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

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"

Publishing engines

Cocoon Java-based

AxKit Perl-based

4Suite Python

Others or roll your own

Viewing the file

If you see the file you wanted to upload and receive a "File written successfully" message...

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

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 "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/