Xalan-Java Overview
- Introduction
- Xalan-Java Features
- Getting to work with Xalan-Java
- Getting up to speed with XSLT
- Glossary
Introduction
Xalan-Java fully implements XSL Transformations (XSLT) Version 1.0 and the XML Path Language (XPath) Version 1.0. XSLT is the first part of the XSL stylesheet language for XML. It includes the XSL Transformation vocabulary and XPath, a language for addressing parts of XML documents. For links to background materials, discussion groups, frequently asked questions, and tutorials on XSLT, see Getting up to speed with XSLT.
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XSL also includes a vocabulary for formatting documents, which is not part of Xalan-Java. For more information, see Extensible Stylesheet Language (XSL) Version 1.1 and the Apache XmlGraphics FOP (Formatting Objects Project). |
XSL stylesheets are written in the XSLT language. An XSL stylesheet contains instructions for transforming XML documents into XML, HTML, XHTML or plain text. In structural terms, an XSL stylesheet specifies the transformation of one tree of nodes (the XML input) into another tree of nodes (the output or transformation result).
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The XSL stylesheet may generate and refer to cascading style sheets (CSS) as part of its output. |
In the following example, the foo.xsl stylesheet is used to transform foo.xml into foo.out:
foo.xml:
<?xml version="1.0"?> <doc>Hello</doc>
foo.xsl:
<?xml version="1.0"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <xsl:template match="doc"> <out><xsl:value-of select="."/></out> </xsl:template> </xsl:stylesheet>
foo.out:
<out>Hello</out>
By default, Xalan-Java uses Xerces-Java, but it may be configured with system properties to work with other XML parsers (see Plugging in a Transformer and XML parser). The input may be submitted in the form of a stream of XML markup (from a URI, a character or byte stream, or another transformation), a SAX InputStream, or a DOM Node.
Xalan-Java performs the transformations specified in the XSL stylesheet and packages a sequence of SAX events that may be serialized to an output stream or writer, used to build a DOM tree, or forwarded as input to another transformation.
Xalan-Java Features
- Includes an Interpretive processor for use in a tooling and debugging environment and
a Compiling processor (XSLTC) for use in a high performance runtime environment.
- Implements the relevant W3C specifications: XSL Transformations (XSLT) Version 1.0 and
XML Path Language (XPath) Version 1.0.
- Implements Java API for XML Processing (JAXP) 1.3, and builds on
SAX 2 and DOM level 3.
- Implements the XPath API in JAXP 1.3.
- May be configured to work with any XML parser, such as
Xerces-Java, that implements
JAXP 1.3 (see Plugging in an XML
parser).
- Can process Stream, SAX or DOM input, and output to a Stream, SAX or DOM.
- Transformations may be chained (the output of one transformation may be the input for
another).
- May be run from the command line for convenient file-to-file
transformations.
- Includes an applet wrapper.
- May be used in a servlet to transform XML documents
into HTML and serve the results to clients.
- Supports the creation of Java and scripting language extensions. and provides a growing library of extension elements and functions.
Getting to work with Xalan-Java
For instructions and some suggestions about how to get started using the XSLT Interpretive processor, see Getting Started with Interpretive Processing.
For instructions and some suggestions about how to get started using the XSLT Compiling processor, see Getting Started with XSLTC.
Getting up to speed with XSLT
If you are still working through the details of the XSLT spec (the W3C 1.0 Recommendation), you may want to consult one or more of the following:
- XSLT - XSL Transformations in
The XML Revolution: Technologies for the future Web by Anders Møller and Michael
I. Schwartzbach (Web pages, but designed for sequential reading)
- Crane Softwright's Free preview of
Practical Transformation Using XSLT and XPath
- Doug Tidwell's XSLT, O'Reilly, 2001
- Bob Ducharme's XSLT Quickly,
Manning Publications, 2001
- John Robert Gardner and Zarella Rendon's
XSLT
and XPath: A Guide to Transformations, Prentice-Hall, 2001
- Michael Kay's XSLT
Programmer's Reference, 2nd ed., Wrox Press, 2001
- Dave Pawson's XSL Frequently Asked Questions to search out particular answers and
techniques
- Miloslav Nic's XSL
Tutorial, a collection of stylesheet examples
- Elliotte Rusty Harold's
Chapter 17 of the XML Bible: XSL Transformations
- The Mulberry XSL-List -- Open Forum on
XSL (of interest to XSL users at all levels)
- Objects by Design's
Transforming XMI to HTML (oriented towards XMI, "an XML-based, stream representation
of a UML model," but also covers "generic" XML transformations) and their related
XSLT by Example
- OASIS (the Organization for the Advancement of Structured Information Standards):
Extensible Stylesheet Language (XSL)
by Robin Cover
When you come across other useful introductory or background materials, please email Xalan Development Mailing List, so we can add them to this list.
Glossary
XSLT Namespace
The XML namespace for XSLT. An XML namespace is a collection of element and attribute names, identified by a Unique Resource Identifier (URI), which often takes the form of a URL, but is really just a unique string, not a pointer to a web page. The XSLT namespace URI is http://www.w3.org/1999/XSL/Transform. In each XSLT stylesheet, you must declare this namespace in the stylesheet element tag and bind it to a local prefix. Like the XSLT specification, we always use xsl as the XSLT namespace prefix in our descriptions and examples, although you are free to bind any prefix to this namespace.
XSL Instruction
Any tag associated with the XSLT namespace.
Template
An element, usually with child elements, that specifies a "rule" or set of instructions to perform when a particular kind of node is encountered in the source tree.
XSL Template Instruction
Any tag that occurs inside an xsl:template element and is associated with the XSLT namespace.
Source Tree
The XML tree input to the XSL process.
Result Tree
The tree that is output by the XSL process.
Match Pattern
The part of a template that defines the kind(s) of nodes to which the template applies.