WNG is a JSP tag-library, what tags really do is to build "components", i.e. to create Java objects which you can connect like Lego bricks to build a mobile page programmatically. The actual rendering is postponed to a later stage, i.e. when the programmer is ready. Of course, the rendering can be made follow the JSP life-cycle (and this will be the most common usage, I suspect), but nothing prevents you, the programmer, from having the object model generate mobile mark-ups in situations I cannot think of at the moment.