JSF - Create a Dynamic Menu by using AJAX & selectOneListbox - ajax

Question

What I'd like to do is simple to explain :
bean
#ManagedBean
#ViewScoped
public class Articles {
private String selectedMenu;
#PostConstruct
public void init() {
if(selectedMenu==null || selectedMenu.trim().isEmpty()) {
this.selectedMenu="0";
}
}
public String getSelectedMenu() { return selectedMenu; }
public void setSelectedMenu(String selectedMenu) { this.selectedMenu = selectedMenu; }
}
page
<h:selectOneListbox onchange="..?? ajax call that render on loadMenu and pass the value of the focused listbox to Articles Bean" id="category" size="0" >
<f:selectItem itemLabel="first" itemValue="0" />
<f:selectItem itemLabel="second" itemValue="1" />
<f:selectItem itemLabel="third" itemValue="2" />
</h:selectOneListbox>
<h:panelGroup layout="block" id="loadMenu">
<h:panelGroup rendered="#{articles.selectedMenu=='0'}">
MENU 0
</h:panelGroup>
<h:panelGroup rendered="#{articles.selectedMenu=='1'}">
MENU 1
</h:panelGroup>
<h:panelGroup rendered="#{articles.selectedMenu=='2'}">
MENU 2
</h:panelGroup>
</h:panelGroup>
When I change the value of the listbox, the menu should change dinamically (by calling some function on the server). I think that the code above expresses what I'm looking for.
I must know how call it using the onchange option. Is it possible?
Cheers
UPDATE
<h:panelGroup layout="block">
<h:selectOneListbox styleClass="article_combo" size="0" id="selectedMenu" >
<f:selectItem itemLabel="first" itemValue="0" />
<f:selectItem itemLabel="second" itemValue="1" />
<f:selectItem itemLabel="third" itemValue="2" />
<f:ajax event="change" execute="#this" render="loadMenu" />
</h:selectOneListbox>
</h:panelGroup>
<h:panelGroup layout="block" id="loadMenu">
<h:panelGroup rendered="#{articles.selectedMenu=='0'}">
MENU 0
</h:panelGroup>
<h:panelGroup rendered="#{articles.selectedMenu=='1'}">
MENU 1
</h:panelGroup>
<h:panelGroup rendered="#{articles.selectedMenu=='2'}">
MENU 2
</h:panelGroup>
</h:panelGroup>

Answer 1

You can use the ajax support built in to JSF 2 to achieve this. To do this nest an f:ajax tag in your h:selectOneListbox tag. The f:ajax tag should look like:
<f:ajax render="loadMenu" execute="#this" />
This should process the changed value in your list box, and re-render the panelGroup.
for further details, see:
http://mkblog.exadel.com/2010/04/learning-jsf-2-ajax-in-jsf-using-fajax-tag/