JAXP Transformation Package and Xalan Extensions

黃立昇91753034

Outline

JAXP Transformation Package Xalan Extensions

JAXP Transformation Package

Packages

javax.xml.transform javax.xml.transform.dom javax.xml.transform.sax javax.xml.transform.stream

javax.xml.transform

Define the generic APIs for processing transformation instructions, and performing a transformation from source to result

Define the factory class to get a Transformer object

We then configure the transformer with the source and result, and invoke the transform() method to do the transformation

javax.xml.transform.*

javax.xml.transform.dom; javax.xml.transform.sax; javax.xml.transform.stream

Define the source and result class that let a dom tree/sax event or I/O stream as an input or output from a transformation

Example-1 (XML -> Stream)

Transformer transformer;TransformerFactory factory =

TransformerFactory.newInstance();String stylesheet = "file:///home/user/mystylesheet.xsl";String sourceId = "file:///home/user/sourcefile.xml";try {

transformer = factory.newTransformer(new StreamSource(stylesheet));transformer.transform(new StreamSource(sourceId),new StreamResult(System.out));

} catch (Exception e) {// handle error}

Example-2 (DOM -> Stream)TransformerFactory tfactory = TransformerFactory.newInstance();

try{Transformer serializer = tfactory.newTransformer();Properties oprops = new Properties();oprops.put(“method”, “html”);oprops.put(“indent-amount”, “2”);serializer.setOutputProperties(oprops);serializer.transform(new DOMSource(doc),

new StreamResult(System.out));} catch (Exception e) {// handle error}

How System Find the TransformerFactory Class

Use the javax.xml.transform.TransformerFactory system property

Use the properties file

“%JAVA_HOME%/lib/jaxp.properties" in the JRE directory. Look for the classname in the file

META-INF/services/javax.xml.transform.TransformerFactory in jars available to the runtime.

Platform default TransformFactory instance.

(org.apache.xalan.processor.TransformerFactoryImpl)

Xalan Extensions

Xalan Introduction

Xalan is a XSLT processor provided by APACHE

It full implements XSLT 1.0 and XPATH 1.0 Include an Interpretive processor (Xalan) for

tools and a Compiling processor (XSLTC) for high performance runtime environment

JAXP Transformation default Transformator

XSLT Extensions

Specified in XSLT 1.0 Recommendation Add the functionally of XSLT to call a

procedural language Allows two kinds of extension

extension elements extension function

Does not provide a mechanism for define implementations of extension

Extension Elements Extension element perform a action not

transfers to the result tree Declare some namespace as extension

namespace, elements in the namespace are recognized extension elements Using an extension-element-prefixes attribute on an

xsl:stylesheet element an extension-element-prefixes attribute on an literal

result element Can contain attributes, text nodes, other

elements or any valid XML

Extension Functions Can think extension functions as extended

core library that XPATH provide If the FunctionName in a FunctionCall

expression in not an NCName (i.e. if it contains a colon ),then it is treated as a call to an extension function

The FunctionName is expanded to a name using the namespace declarations from the evaluation context

Pass arguments and returns a value

Support Languages

JavaScript NetRexx BML JPython

Jacl JScript VBScript PerlScript

Direct supported by java Use BFS (Bean Scripting Framework)

A Simple Examplehttp://www.cs.nccu.edu.tw/~g9134/XML/simple_example.xslt The source element contains a numdays

attribute (<deadline numdays=“3”/>) The extension element contains a multiplier

attribute to set variable in the extension The extension function compute the deadline

(current date+numdays*multipler) The result transformation of the deadline

element will be:

<p>We have logged your enquiry and will respond by April 29, 2000 12:07:16 PM EST.</p>

Syntax

1. Declare the xalan namespace

2. Declare a unique namespace for each extension prefix

3. If using extension elements, designate the extension element prefixe

4. (Optional) Exclude the extension namespace declaration from the result tree

exclude-result-prefixes="prefix-1 prefix-2 ...“ for element xsl:exclude-result-prefixes="prefix-1 prefix-2 ...“ for literal result

5. Set up an xalan:component

6. Set up an xalan:script element

Extension Element Implementation

Type element

(org.apache.xalan.extensions.XSLProcessorContext, org.apache.xalan.templates.ElemExtensionCall extensionElement)

XSLProcessorContext provides access to the XSL processor,the XML source tree,the stylesheet tree,the current context node, and current mode

ElemExtensionCall provide the API for interacting with the extension element

The value returned by an extension element is placed in the transform result

If not interested in the return value, return null instead

Extension functions

Can be think as a extension of XPATH core function

May include arguments of any type and return a value of any type

If using java, Xalan-Java will automatically mapping xslt data typesto a corresponding java type(class) when passing arguments and return values (Node-set, String, Boolean, Number, Result Tree Fragment)

Any non-XSLT type is passed without conversion

Extensions Library Extension element and function provide a

powerful mechanism for extending and simplifying what we can do with XSLT processor

EXSLT provide a set of standard extension functions and elements to XSLT users Commom, math, set, date-and-time, dynamic,

string

Xalan Extension Library

Support EXSLT standard extension library Redirect, nodeset, NodeInfo, SQL,

PipeDocument, evaluate, tokenize

Redirect

Can used to redirect portions of your transformation output to multiple files

Supply three extension elements <open> <write> <close>

Examplehttp://plum.cs.nccu.edu.tw/~g9134/XML/redirect.xslt

Source document<?xml version="1.0"?>

<doc> <foo file="foo.out">

Testing Redirect extension: <bar>A foo subelement text

node</bar> </foo> <main> Everything else </main>

</doc >

The output redirected to foo.out<?xml version="1.0" encoding="UTF-8"?> <foo-out>

Testing Redirect extension: <foobar-out>foo subelement text node</foobar-out>

</foo-out>

The standard output<?xml version="1.0" encoding="UTF-8"?>

<standard-out>Standard output: <main> Everything else. </main>

<standard-out>

Reference

JAXP spec.

(http://java.sun.com/) The java web service tutorial

(http://java.sun.com/) Xalan-Java

(http://xml.apache.org/xalan-j/index.html) EXSLT

(http://exslt.org)