Hi we are using ejb3 stateless session bean. We use standalone class for validation.
Standalone class loads the xml file (uses dom parser) and that class uses singleton pattern. That class was called all our ejb bean to validate certain functionality. Over the period of time (about 30 days) xml parser could not able to provide xml nodes which was failing the validations. I couldn't able to find out the reason. After we restarted the server again it works fine. We are using the same functionality over 2 years and this was the first time we encounter this issue.