// Upon office selection, get employees related to the selected office:
Collection<IEmployee> employees = store.getEmployeesByOffice(store.getOffice(officeId));
// Create the component to render (a list of html option element):
List options = new LinkedList();
Option first = new Option("-1", "Select one ...");
options.add(first);
for(IEmployee emp : employees) {
Option option = new Option(emp, "matriculationCode", "surname");
options.add(option);
}
// Create an ajax action for replacing the content of the "employees" element:
ReplaceContentAction action = new ReplaceContentAction("employees", options);