@Xinhua, that's an interesting way of doing it and feels more Seam-like than using a Servlet. Have you had any problems with xhtml and the ajax4jsf filters interfering with ExtJS? One advantage of the servlet approach is that the page loads with the grid/tree and then the call is made to the backend. Using a4j:jsFunction wouldn't the call be made to collect the data before the page is rendered - ie. introducing a delay in the page render? Cheers, Damian. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4106356#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...