How to use Ajax with WebSphere Portal?

To add Ajax to a portal application, one need a secondary controller such as servlet or web service to separate the model logic. This controller is to perform the communications with the Ajax client. We can either bundle this controller with the portlet WAR or include as a part of stand-alone web application. The figure below shows this architecture.

Ajax in Portal

If the Ajax controller servlet bundles with the portlet WAR, application can share session data between the servlet and portlet.