XSLT (Extensible Stylesheet Language Transformations) is a language for transforming XML documents into other XML
documents, or other formats such as HTML for web pages, plain text or XSL Formatting Objects,
which may subsequently be converted to other formats, such as PDF, PostScript and PNG.
The XSLT processor is part of Axional Server core services and it's commonly used
to transform XML documents into FO XML documents prior to be sent to the FOP processor.
1 Saxon vs Xalan
Axional Server supports either Xalan
and Saxon XSLT processors.
Saxon 9 is actively developed while Xalan development is stalled since many years.
This is also because Saxon 9 is an XSLT 2 procesor while Xalan is an XSLT 1 processor.
There is no point in struggling with XSLT 1 while XSLT 2 is available since a few years already. Xalan is licensed under Apache 2.0 and Saxon is licensed under Mozilla Public License (MPL).
From a usage point of view there is not really a difference - it will be a difference only if you change the processor code yourself, in case of MPL you need to make available your changes to the code.
1.1 Saxon issues
One issue with Saxon 9 HE is that it does not support extensions directly, but you can register integrated extensions
though the API or by passing an Initializer class in the command line that will register those extensions. However,
XSLT 2.0 provides many new functions and instructions as standard so it is less likely that you will need extensions.
Any way, integrate a Java function is not as easy as in Xalan.
We can read about
Saxon Java integration using Saxon HE from
here
Another issue with Saxon 9 HE is that it does not support javascript calls. So the Xalan with Mozilla Rhino
integration is a key point in favor of Xalan when javascript is need.
Saxon 9 also includes support for XSLT 3.0 (currently this is a working draft) but with Saxon you have early access
to some of the new additions in XSLT 3.
2 Command line processor
The XSL processor can be run from command line using the followning command:
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$ bin/XSLProcessor.sh -xsl {file} -xml {file} -out {file} [-encoding {encoding}]
| Argument | Description |
|---|---|
| xsl | xsl transformation file |
| xml | xml file with xml data to transform |
| out | output transformed file |
| encoding | file encoding (default is utf-8) |
3 Selecting XSL the processor
Server can select either Xalan or Saxon XSLT procesors. By default Xalan is preferred
cause if supportes either java and javascript call during XSLT transform.
Selecting the XSL processor can be done by:
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TransformerFactory xalan = XMLFactory.getDocumentBuilderFactory(DocumentBuilderType.XALAN); TransformerFactory saxon = XMLFactory.getDocumentBuilderFactory(DocumentBuilderType.SAXON);
4 Selecting XML the processor
The same way, you can select the XML processor to be used and select either Xerces
or Saxon.
Selecting the XML processor can be done by:
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DocumentBuilderFactory xerces = XMLFactory.getDocumentBuilderFactory(DocumentBuilderType.XERCES); DocumentBuilderFactory saxon = XMLFactory.getDocumentBuilderFactory(DocumentBuilderType.SAXON);