[drupal-support] drupal integration with java

Has anyone integrated drupal with a java app (a large number of java classes, and a lot of jsp's too). The Java app runs on tomcat. I have come across some php-java integration projects on google. Any ideas on this would be welcome. The idea is that the java app has a badly written user/password/menu etc module. I would like to strip out all that and use drupal for that. The app is too large and complex to rewrite. i have thought of web-services. re, rahul benegal