Postback and AJAX

Throughout this book, we have mentioned the postback request several times. For those who are not familiar with it, or just need a quick reminder, let's say that JSF recognizes the initial request and the postback request.

Initial request (for example, HTTP GET) is the first request that the browser sends for loading the page. You can obtain such a request by accessing the application URL in a browser or by following a link (it can be a link to any page of the application). Moreover, the initial request happens in page_B when page_A contains a redirection (faces-redirect=true) to page_B (this is not true for forwarding mechanism). This kind of request is processed in Restore View phase and Render Response phase.

Postback request happens when we click on a button/link for submitting a form. Unlike the initial request, the postback request passes through all the phases.

JSF provides a method named isPostback that returns a Boolean value: it returns true for postback request...