[xwiki-devs] Access to XWiki from HttpServlet

I have a servlet I am porting from another environment that only needs a few services from XWiki (mostly user authentication and group membership). Is there a recommended way of getting a handle to an XWiki instance from a servlet that derives from HttpServlet? I was looking for some sort of static method I could invoke to retrieve this but haven't come across one yet. Suggestions would be appreciated. Thanks, Glenn