Java Server Faces JSF, is fast replacing Struts Framework in web applications. The JSF is component based, event driven architecture. The various elements of html pages are shown in form of components. Many IDEs are providing drag and drop functionalities for adding the components to the Web pages.
The event, which is triggered by each component, have a listener, which can take the appropriate action. JSF and portlets seems to form a good combination. Sun have already used this technology in their Sun Portal Server. They are providing Ajax support with JSF Portlets. The Sun Studio can develop the JSR168 portlets using JSF. It should be possible that each component of the JSF is able to be rendered independently through Ajax in future.