I used JBoss extension Service Bean as a singelton control. However, it does not prevent concurrency to call this service Bean. Multi-threadings could call the API in this service Bean at the same time. Seems container control on the bean pool is not effective for service Bean. Is this true? If yes, what's the best way to design a singelton stateless session Bean? I tried Jboss PoolClass, but it is so odd to compile.