The Reverse Asynchronous JavaTM and XML (AJAX) technology enables dynamic content to be delivered to the browser, thus improving application performance by eliminating the need for constant polling. This technology can be used in many scenarios to deliver an excellent user experience.

For example, a news portal can push the news to a user's browser when it becomes available, without needing user action and without needing to keep refreshing or re-rendering the whole page. Another scenario is to display an up-to-date task list to which the server pushes the new task once it is created, so that the task owner doesn't need to keep pulling the updates.

In this article we go through all the steps needed to leverage Reverse AJAX in portlets using Dojo CometD implementation. We develop a Task List portlet that displays a set of tasks assigned to the logged-in user and to which the server keeps pushing any new tasks, using reverse AJAX.