RE: [xsl] Chaining Transformers/Templates

["Michael Kay" <michael.h.kay@xxxxxxxxxxxx>]

Two of the classes mentioned, XMLReaderFactory and SerializerFactory,
aren't in JAXP: any reason why you're not writing pure JAXP code?

The XMLReader and the TransformerHandlers are serially reusable but not
multithreaded. It's generally best to create a new instance of these
classes for each transformation, if only to be sure of clearing out
unwanted data in memory. The important object to reuse is the Templates
object.

Michael Kay
Software AG
home: Michael.H.Kay@xxxxxxxxxxxx
work: Michael.Kay@xxxxxxxxxxxxxx  

> -----Original Message-----
> From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx 
> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Varley, Roger
> Sent: 10 December 2002 13:01
> To: 'xsl-list@xxxxxxxxxxxxxxxxxxxxxx'
> Subject: RE: [xsl] Chaining Transformers/Templates
> 
> 
> > 
> > > The reason that I want to to use Templates is that I
> > > will have a large number of threads performing a 
> > > transormations using two standard XSL stylesheets so I want 
> > > to avoid the overhead of re-processing the transform 
> > > instructions every time. 
> 
> Thanks to Micheal Kays response I now have the following code 
> running and working in the processing threads.
> 
>            TransformerFactory tFactory = 
> TransformerFactory.newInstance();
>            SAXTransformerFactory saxFactory = 
> (SAXTransformerFactory) tFactory;
>            
>            TransformerHandler standardTH = 
> saxFactory.newTransformerHandler(standardTemplate);
>            TransformerHandler recipientTH = 
> saxFactory.newTransformerHandler(recipientTemplate);
>            
>            XMLReader reader = XMLReaderFactory.createXMLReader();
>            reader.setContentHandler(standardTH);
>            standardTH.setResult(new SAXResult(recipientTH));
>            
>            Serializer serializer = 
> SerializerFactory.getSerializer(OutputProperties.getDefaultMet
> hodProperties(
> "xml"));
>            serializer.setOutputStream(new 
> FileOutputStream(incomingPath + "result.xml"));
>            
>            recipientTH.setResult(new 
> SAXResult(serializer.asContentHandler())); 
> 
> The template objects are created by an external singleton 
> class called by the processing thread. The singleton class has to call
> TransformerFactory.newInstance() to create the template, so 
> I'm now wondering how much of the above code I can move to my 
> external singleton class and still remain threadsafe. For 
> example, could I go as far as moving all this code to my 
> external class so that the XMLReader is only built once and 
> return the XMLReader object to every thread that asks for it. 
> The thread then builds the input for the XMLReader and then 
> calls XMLReader.parse().
> 
> Regards
> Roger 
> 
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