A session bean is created by a client and usually exists only for the duration of a single client/server session.
A session bean performs operations, such as calculations or accessing a database, for the client. While a session
bean may be transactional, it is not recoverable should a system crash occur. Session bean objects can be either
stateless or they can maintain conversational state across methods and transactions. If they do maintain state,
then the EJB container manages this state if the object must be removed from memory. However, the session bean
object itself must manage its own persistent data.