7.2.1 Stateless session beans
By definition, a stateless session bean maintains no state information. Each client request directed to a stateless session bean is independent of the previous requests that were directed to the bean. The EJB container maintains a pool of instances of stateless session beans, and provides an arbitrary instance of the appropriate stateless session bean when a client request is received. Requests can be handled by any stateless session bean instance in any cluster member of a cluster, regardless of whether the bean instance handled the previous client requests.
Workload management can be applied to the Home object and the bean instance of a given stateless session bean. Therefore, the stateless session bean is a perfect programming model when constructing a well-balanced and highly available enterprise application.