Notifications

Often it is the case that you want to be able to check for any error conditions that occurred during an Ajax request and trigger the update of a notification area if there was a problem. AjaxResponseAppender provides an API to perform these kinds of checks on all ajax requests.

Exceptions

You want to handle exceptions differently for Ajax than non-Ajax updates. In an Ajax update, you can't just generate an exception page, because you're typically performing a partial update. Instead one approach is to just render the exception error message inline with the response, as demonstrated here.

Session Timeouts

Just like exceptions, session notifications should be handled with a different technique. Rather than render the session timeout page, you can generate a redirect with Javascript in response to a session timeout. Click "Generate Session Timeout" one more time to see how Ajax session timeouts can be handled.