I had a play with the tree column component and used the json.org classes (which I jar'd up) and pumped the JSON out with a servlet using Beans that had a toJSONObject() method. I tried using XStream and Jettison but the JSON produced was not valid for Ext. It all worked when the page extension was .html but not when .xhtml. I'm not sure what caused this. I'll be looking into it again soon. Keen to hear how others have done this. I think Seam Remoting could be a better option. I know there are several people on the Ext forums using Seam as a backend. Cheers, Damian View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4106272#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...