XSLT and XPath - Advance Java Web Technology - Lecture Slides, Slides of Computer Science

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XSL

XSLT and XPath

What is XSL?

• XSL stands for Extensible Stylesheet Language
• CSS was designed for styling HTML pages, and can be used to style XML pages
• XSL was designed specifically to style XML pages, and is much more sophisticated than CSS
• XSL consists of three languages:
  • XSLT (XSL Transformations) is a language used to transform XML documents into other kinds of documents (most commonly HTML, so they can be displayed)
  • XPath is a language to select parts of an XML document to transform with XSLT
  • XSL-FO (XSL Formatting Objects) is a replacement for CSS
    • There are no current implementations of XSL-FO, and we won’t cover it

Simple XPath

• Here’s a simple XML document:

 XML Gregory Brill Java and XML Brett McLaughlin - XPath expressions look a lot like paths in a computer file system - / means the document itself (but no specific elements) - /library selects the root element - /library/book selects _every_ book element - //author selects _every_ author element, wherever it occurs 

Simple XSLT

• loops through

every book element, everywhere in the

document

• chooses the

content of the title element at the current

location

•

chooses the content of the title element for each

book in the XML document

What we need to do

• We need to save our XML into a file (let’s call it

books.xml)

• We need to create a file (say, books.xsl) that

describes how to select elements from

books.xml and embed them into an HTML page

• We do this by intermixing the HTML and the XSL in the

books.xsl file

• We need to add a line to our books.xml file to

tell it to refer to books.xsl for formatting

information

books.xml, revised

•  XML Gregory Brill Java and XML Brett McLaughlin 

This tells you where to find the XSL file

XSL outline

...

Selecting titles and authors

Book titles:

Book authors: ...same thing, replacing title with author

 Notice that XSL can rearrange the data; the HTML result can present information in a different order than the XML

Notice the xsl:for-each loop

All of books.xsl

Book Titles and Authors

Book titles:

Book authors:

How to use it

• In a modern browser, such as Netscape 6,

Internet Explorer 6, or Mozilla 1.0, you can just

open the XML file

• Older browsers will ignore the XSL and just show

you the XML contents as continuous text

• You can use a program such as Xalan, MSXML,

or Saxon to create the HTML as a file

• This can be done on the server side, so that all the

client side browser sees is plain HTML

• The server can create the HTML dynamically from

the information currently in XML

The End