title: XML Diff and Merge
body: <p>I think i have a rather unique problem to solve. Well, i cant find enough information using Google. So here it goes,</p>
  
  <p>I work on a Java EE SOA application which stores XML documents as XML using Oracle XML DB. Whenever the XML changes, i increment the version and throw the previous version into a different table. </p>
  
  <p>The requirement now is, I should store the differences between 2 versions as XML, instead of the whole XML document. </p>
  
  <ol>
  <li>Is there any Java library which can do XML comparison? (XMLUnit, ... ?)</li>
  <li>Is there a standard XML Schema for capturing XML differences? </li>
  <li>What transformation technology can i use to apply the "differences" to an XML to go back and forth between versions? (XSLT, Groovy,.... ?)</li>
  </ol>
  
  <p>I appreciate your time.</p>