This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
It is definitely not recommended way of using session beans. Two or more clients invoke business method on the same instance of EJBObject simultaneously can be done via user developed multi-threaded program, which is a strict no-no in EJBs. The obvious problem areas would be transaction, security management.
subject: Will the singleton use on EJBObject cause problem?