After going though the JCA specs I could make that there is one-one relationship between ConnectionEventListener AND ManagedConnection. In the BaseWrapperManagedConnection I can see private final Collection cels = new ArrayList(); The closeHandle(Object) in the BaseWrapperManagedConnection has synchronized(cels) | { | copy = new ArrayList(cels); | } | for (Iterator i = copy.iterator(); i.hasNext(); ) | { | ConnectionEventListener cel = (ConnectionEventListener)i.next(); | cel.connectionClosed(ce); | } which could have been replaced by cel.connectionClosed(ce) if we have this private final Collection cels = new ArrayList(); replaced by private ConnectionEventListener cel ; I am not able to understand why we have ConnectionEventListener associated with ManagedConnection stored as ArrayList as I expect this ArrayList will always have single CEL. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4112183#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...