October 13, 2005

Using XT with Cocoon

As some of you know, recently over at Cocoon GetTogether 2005, we had a presentation about XSLT processors performance in Cocoon environment. Results for Xalan, Saxon, XSLTC were presented. Soon after that Upayavira mentioned that XT is out of hibernation and gets some maintenance (apparently by XMLEcho / Palomar guys), and he suggested to run tests against XT as well.

It's easier said than done, as people say... It all started out just peachy: XT Release 20050823 promised SAX2 and JAXP, so may be it has TrAX as well, and it did not take me long to get name of transformer factory: 

    com.jclark.xsl.trax.TransformerFactoryImpl

Excellent. I drop xt jar into WEB-INF/lib, start up servlet engine... On the first request it blows with exception: 

    no such prefix: xsl
It happened when it was trying to parse <xsl:stylesheet> element (that's when I understood it won't be easy...). Culprit of lost namespaces was the way how namespaces were processed: 
    public void startPrefixMapping(String prefix, String uri)
    {
        // I think we'll just extract 'em from the attributes
    }
Which gave a clue that it might work with name space prefixes enabled: 
<xml-parser class="org.apache.excalibur.xml.impl.JaxpParser">
  ...
  <parameter name="namespace-prefixes" value="true"/>
  ...
</xml-parser>
And miracle happened! It did worked! Till it hit an NPE telling me that some XMLReader was not initialized somewhere within it guts... Patched it in com.jclark.xsl.trax.TransformerFactoryImpl:
public TemplatesHandler newTemplatesHandler()
    throws TransformerConfigurationException
{
    try {
        XMLReader reader = newDefaultReader();
        reader.setFeature("http://xml.org/sax/features/namespaces", true);
        reader.setFeature("http://xml.org/sax/features/namespace-prefixes", true);

        return new TemplatesHandlerImpl(this, new XMLProcessorImpl(reader));
    } catch(Exception e) {
        throw toConfigException(e);
    }
}
Failed with NPE. Now I found out it is not fully yet integrated with Jaxp... It could not find SAXParser. Here we go: 
    set JAVA_OPTS=
        -Dorg.xml.sax.parser=org.apache.xerces.parsers.SAXParser
Moving further... Failed with TransformerConfigurationException: 
Caused by: javax.xml.transform.TransformerConfigurationException:
    newTransformerHandler(Templates templates) not yet implemented
	at com.jclark.xsl.trax.TransformerFactoryImpl.
            newTransformerHandler(TransformerFactoryImpl.java:404)
Showstopper. No TrAX for us.

To be continued...

Posted by Vadim at October 13, 2005 8:48 PM