What do you get with variableResolver, a session with user's access?
There is also the DominoUtils class which has 3 different methods for getting session, I'm not sure what's the difference between them:
http://www.timtripcony.com/xpages_ext_api_javadoc/com/ibm/xsp/model/domino/DominoUtils.html
I'm always passing the session to my Java classes to make them reusable from agents, web services and servlets.