My misunderstanding or the mistake of the doc? It's like below before: @Name("chatroom") public class Chatroom { @In PojoCache pojoCache; public void join(String username) { try { Set userList = (Set) pojoCache.get("chatroom", "userList"); if (users==null) { userList = new HashSet(); pojoCache.put("chatroom", "users", username); } } catch (CacheException ce) { throw new RuntimeException(ce); } } } View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4023036#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...