XSLT transformations from Ant

It is possible to run a Saxon transformation from Ant using the standard xslt task, by using the trax processor and with an appropriate classpath that forces Saxon to be selected. This can now be used to provide the ability to take advantage of the full range of capabilities offered by XSLT 3.0 in general and Saxon in particular (for example, schema aware processing and multiple output files).

To ensure that Saxon is the chosen XSLT processor it is safest to use the <factory name="factory-class"> element in the the Ant task. The relevant factory classes are:

• net.sf.saxon.BasicTransformerFactory for Saxon-HE
• com.saxonica.config.ProfessionalTransformerFactory for Saxon-PE
• com.saxonica.config.EnterpriseTransformerFactory for Saxon-EE
• com.saxonica.config.StreamingTransformerFactory for a streaming transformation in Saxon-EE. Note that if this option is selected, the global context item for the transformation (used when a global variable initializer references the context item) will be absent, so any reference to "." in a global variable throws an error.

Saxon-specific configuration options can be specified using the attribute child of the factory element. For example, the following switches on Saxon tracing (the equivalent of the -T option on the command line):

<factory name="net.sf.saxon.TransformerFactoryImpl"> <attribute name="http://saxon.sf.net/feature/traceListenerClass" value="net.sf.saxon.trace.XSLTTraceListener"/> </factory>

For a full list of feature names, see Configuration features or the Javadoc documentation of class net.sf.saxon.lib.Feature.

A particularly useful feature for use with Ant is http://saxon.sf.net/feature/ignoreSAXSourceParser. When Ant invokes Saxon, it normally does so supplying a SAXSource object with a contained XMLReader. Saxon will not normally change the properties of an XMLReader supplied by the application. However, allowing Saxon to supply its own XMLReader can be much more efficient, especially in the case where there are references to W3C-defined HTML or SVG DTD and entity files: Saxon has internal copies of these files, but can only use them if it is allowed to configure the parser accordingly. Setting this property authorises Saxon to ignore the parser supplied by Ant and use its own.

It is possible to get detailed control of the configuration by specifying the name of a Saxon configuration file using this mechanism, for example:

<factory name="com.saxonica.config.EnterpriseTransformerFactory"> <attribute name="http://saxon.sf.net/feature/configuration-file" value="config-de.xml"/> </factory>

In this case this must be the first attribute.

The initial template and initial mode for the transformation can be specified using the attribute names http://saxon.sf.net/feature/initialTemplate and http://saxon.sf.net/feature/initialMode respectively. The value is a QName in Clark notation (that is {uri}local).

Note that names in Clark notation may also be used for the qualified names of stylesheet parameters and serialization options.

Note that an Ant transformation always has an input file. If necessary, a dummy file can be specified.

There is a history of bugs in successive releases of Ant that mean not all these features work in every Ant version. In particular, the classpath attribute of the xslt task element has been unreliable: the safest approach is to ensure that the Jar files needed to run Saxon are present on the externally-specified classpath (the classpath at the point where Ant is invoked), rather than relying on the task-specific classpath.