Lecture Slides on XSLT - Distributed Software Develop | CS 682, Study notes of Software Engineering

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Distributed Software Development

XSLT Chris Brooks

Department of Computer ScienceUniversity of San Francisco

Department of Computer Science — University of San Francisco – p.1/

7-0:^ XSLT

XSLT is an XML-based language that allows you to declaratively

specify how a document should be changed or transformed.^ You specify the output for a particular element; no needto manage tree traversal. Useful for:^ Emitting an HTML display of an XML document^ Converting between tag vocabularies^ Extracting plain text from an XML document^ AUtomatically modifying or filtering an XML document.

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7-2:^ Our CD database

Beatles

^

Revolver

^

Rock^

5

2:57^

6 ^ Feb^ ^2005 ...

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7-3:^ Step 1: Using XSLT to emit plain

text

To begin, let’s use XSLT to print a plaintext version of ourcatalog. We can run XSLT from the command line or within abrowser.^ /usr/bin/4xslt on nexus^ Most modern browsers have XSLT support^ Debugging is easier from the command line

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7-5:^ Emitting HTML

We can also emit other markup languages, such asHTML. (XHTML, actually). Just indicate the tags to be produced by a template match.

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7-6:^ Emitting XML

We can also use XSLT to create new XML documentswith different tag names or contents. For example, let’s say we want to change the tags to be inSpanish.

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7-8:^ Incorporating CSS

We can still use CSS to control presentational elements. With HTML, we can just embed a ’link’ tag in thegenerated HTML.

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7-9:^ Incorporating CSS

If we’re emitting XML, we can instead embed a

processing

instruction

into the output document. Note: this will work best if we do the XSLT on the serverside.^ <xsl:processing-instruction

name="xml-stylesheet">

href="songs.css"

type="text/css"</xsl:processing-instruction>

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7-11:^ Xpath

The examples we’ve seen so far match templates toelements based solely on the element’s tag name. Often, you want something more flexible:^ Match the root element^ Match all text nodes^ Match all children of an author node Essentially, we want to specify matching rules based onan element’s position in the DOM tree. XPath is a language for doing this.

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7-12:^ XPath

In XPath, everything is dealt with as a path from the rootof the tree. To find a node, we’ll use a

location path

, which consists of

a series of

location steps

A location step consists of:^ An axis that tells us which direction to travel^ A node test that specifies which types of nodes apply^ predicates that use boolean tests to help filter nodes.

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7-14:^ Node test

The second component of the location step is the nodetest. This is joined to the axis by a :: Some tests:^ / - root node^ * - any element^ author - any node named “author”^ text() - any text node In our Tolkien example, we might usebook/volumes/volume::”The Two Towers”

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7-15:^ Shortcuts

// - descending from the root. //volume matches all volumenodes below the root. ../* - all siblings .. - parent /* - document element @name - matches attribute named ’name’

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7-17:^ Predicates

If you need more flexibility in specifying nodes of interest,you can use a predicate. Predicates are contained inside square brackets. To be included in final node set, a node must pass bothaxis and predicate tests.

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7-18:^ Examples

//song/[id=”s1”]/title/text - text for all ’s1’ songs. //song[title] - all quotations that have a source subelement. //song[not(source)] - songs that do not have a titlesub-element. //song[position() == 2] or //song[2] - the second quotation.

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