Abstract. Rich Internet applications (RIAs) enable novel usage scenarios by overcoming the traditional paradigms of Web interaction. Conventional Web applications can be seen as reactive systems in which events are 1) produced by the user acting upon the browser HTML interface, and 2) processed by the server. In RIAs, distribution of data and computation across the client and the server broadens the classes and features of the produced events as they can originate, be detected, notified, and processed in a variety of ways. Server push technologies allow to get over the Web “pull” paradigm, providing the base for a wide spectrum of new browser-accessible collaborative on-line applications. In this work, we investigate how events can be explicitly described and coupled to the other concepts of a Web modeling notation in order to specify server push-enabled Web applications.