Is it possible to restrict the object creation for stateless session beans

Question

Hi,
Is it possible to restrict/fix the ejb object creation for stateless session beans in application server?
For example, i want to configure the application server ( am using JBOSS ) to create maximum of 10 session bean objects. and if any requests for the stateless session bean come, as application server has created 10 objects, the requests should be blocked.
Thanks in advance,
nvseenu

Answer 1

You can keep a counter in the application code. A static var won't work, but an entity and a consistent id should. This version would affect performance, but it would be portable to other app servers.
// ConstrainedBean.java
package unq.ejb;
import javax.ejb.Stateless;
import javax.ejb.CreateException;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.persistence.PersistenceContext;
import javax.persistence.EntityManager;
@Stateless
public class ConstrainedBean implements Constrained {
    final static int DEFAULT_COUNTERID = 1;
    @PersistenceContext EntityManager em;
    @PostConstruct
    protected void init() throws CreateException {
     ConstrainedBeanCounter counter =
         em.find(ConstrainedBeanCounter.class, DEFAULT_COUNTERID);
     if( counter == null ) {
         counter = new ConstrainedBeanCounter();
         counter.counterId = 1;
         counter.counterValue = 0;
         em.persist(counter);
     if( counter.atMaximum() ) {
         throw new CreateException("error attempting to create > 10 beans");
     else {
         counter.increment();
    @PreDestroy
    protected void destroy() {
     ConstrainedBeanCounter counter = em.find(ConstrainedBeanCounter.class,
                               DEFAULT_COUNTERID);
     counter.decrement();
    public void doSomething() { System.out.println("doSomething()"); }
// ConstrainedBeanCounter.java
package unq.ejb;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class ConstrainedBeanCounter implements java.io.Serializable
    @Id public int counterId;
    public int counterValue = 0;
    public void increment() {
     counterValue++;
    public void decrement() {
     counterValue--;
    public boolean atMaximum() {
     return counterValue > 9;
}