This week's book giveaways are in the Refactoring and Agile forums. We're giving away four copies each of Re-engineering Legacy Software and Docker in Action and have the authors on-line! See this thread and this one for details.
Yes, instance variables would be available. In general this is a Bad Idea since Servlets are multithreaded and accessing instance variables would produce race conditions galore. Synchronizing instance variables to prevent race conditions, on the other hand, reduces the efficiency of multithreading.