"mohitanchlia" wrote : Thanks I already looked at it. How is Barrier able to start or stop EJBs, MDBs that are not mbean and don't follow service life cycle i.e start/stop/create etc. In JBoss 4.x? Everthing ends up as an mbean. You add a a "depends" element to the relevant deployment descriptor (jboss-app.xml if an ear, jboss.xml for for EJB/MDB). anonymous wrote : Also, what happens if Election policy like pickSingleton has a bug and chooses 2 nodes as Master at the same time? Then whatever depends on the barrier ends up being started on 2 nodes at the same time. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4188855#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...