The BlockUI component can be used to block other JSF UI components during AJAX processing. With the special AJAX integration, AJAX requests from any of the trigger components will block the UI component for the
onstart event and unblock for the
We may want to block a particular UI component or even entire page while some background processing is running. For example, when we submit a form, we may want to block the form to prevent users from doing any action on the form until the response is received from the server.