A few last minute comments: 1. putIfNull -> putIfAbsent, See http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/ConcurrentMa... . People might get confused with "null" versus absent. 2. Remove the print* methods in NodeSPI. Or at least document them. Consider creating a separate util class to print a node. 3. removeChildDirect(Fqn) and removeChildDirect(Object) is a little confusing, since Fqn is a subtype of Object. I would probably suggest just having one or the other. 4. Some of the NodeSPI data methods appear to be just convenience methods and aren't strictly necessary given that getDataDirect() returns an externally modifiable map. For instance, clearDataDirect() really just is the same as NodeSPI.getDataDirect().clear(). So, it would be nice to understand the reason for these extra methods. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3999669#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...