The <a4j:push> periodically perform AJAX request to server, to simulate 'push' data.

<a4j:push> makes request to minimal code only (not to JSF tree) in order to check the presence of messages in the queue. If the message exists the complete request will be performed. The component doesn't poll registered beans but registers EventListener which receives messages about events.

Attribute 'interval' is used as for poll component. It specifies the interval in ms. for call push request. Simple example of usage: