Best class to use to cache an XML document

Question

Hello all,
I have an utility class representing an XML document, used withing a web application. This document shall be cached in the session since within a request and during the sessions I read it often and to several other things like XPath and XSLT.
But I am having problems due to this Bug:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6322678
and keep bad file descriptor errors due to these stream "specialities". There is a standard way of using cached+precompiled XSL templates and I wonder if there is a similar things for XML documents.
So I need an internal variable in my class containing the raw XML document - so using streams is not an ideal solution in regards of the bug - i am getting "bad file descriptor" errors from time to time.
I am playing with the idea of storing the XML document within a simple String and create the required Class from it for the according operations like XPath evaluation and XSL transformation. But I think that is quite more resource hungry than reading the XML document from the filesystem each time...
Has anyone some hints on how to keep an XML document in memory internally?
Thanks and regards,
Timo

Answer 1

Rehi,
So, everything works really fine! Thanks. As promised, here some examples
with bad indentations etc...:
Doing XSL transformation:
import java.io.StringWriter;
import org.w3c.dom.Document;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.Templates;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.stream.StreamResult;
TransformerFactory tFac = TransformerFactory.newInstance();
Templates compiledXslt = tFac.newTemplates(sheet);
Transformer transformer = compiledXslt.newTransformer();
StringWriter sw = new StringWriter();
StreamResult sr = new StreamResult(sw);
transformer.transform(new DOMSource(this.doc), sr);
System.err.println(sw.toString());************************
Doing XPath was a surprise and was originally my problem (I called evaluate() with an InputStream that occassioannly failed), I tried also here with new DOMSource() what also failed although not being null or so... funny: evaluate() can directly be called w/ dom.Document:
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
(this.doc is a org.w3c.dom.Document)
public String getXPathEvaluationAsString(String expr) {
     try {
          XPath xp = XPathFactory.newInstance().newXPath();
          return (String)xp.evaluate(
               expr,
               this.doc,
               XPathConstants.STRING
     } catch(Exception e) {
          e.printStackTrace();
     return " ";
}Thanks and regards,
Timo