XML Parsing with XSL Performance lag

Question

Hi there
I should qualify this post by saying I am fairly new to EJB's and have based the below on a Java Working with XML Tutorial I read.
I have an EJB which is being developed to parse XML documents with an XSL stylesheet and return HTML for display. The code is working fine however there is a fairly hefty performance lag when using the EJB to generate the HTML as opposed to the straight HTML. I am getting an average response time of 95000ms using the EJB as opposed to 45000ms when viewing the straight HTML. The code I am using to do the parsing is :
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(dataFile);
// Convert docs into StreamSource
StreamSource stylesource = new StreamSource(styleSheet);
StreamSource source = new StreamSource(dataFile);
StringWriter strWrite = new StringWriter();
StreamResult result = new StreamResult(strWrite);
// Use a Transformer for output
TransformerFactory tFactory = TransformerFactory.newInstance();
Transformer transformer = tFactory.newTransformer(stylesource);
transformer.transform(source, result);
There is then some error handling and the strWrite object is placed into an array to be returned.
I am really looking to find out if the performance lag I am experiencing is normal or if there is anything I can do to improve the speed of the code.
All comments and help is most appreciated.
Cheers
Justin.

Answer 1

You should be able to increase performance by caching Templates objects in memory as a previous post suggested.
Here is some untested code:public final class TransformerCache
     private static Map cache = new Vector();
     private TransformerCache(){}
     public static Transformer getTransformer( String filename )
          if( ! cache.containsKey( filename ) )
               TransformerFactory tf = TransformerFactory.newInstance();
               Templates template = tf.newTemplates( new StreamSource( filename ) );
               cache.put( filename, template );     
          return ( ( Templates ) cache.get( filename ) ).newTransformer();
}This aproach works in a clustered environment, just bear in ming that there will be an instance of the cache on each server instance (virtual machine).