Is there any way to send immediately a response to the client (a waiting page) and continue execution until sending the definitive response?
I'm working with Symfony2 (PHP).
Only by adding a refresh meta tag in the html (http://webmaster.iu.edu/tools-and-guides/maintenance/redirect-meta-refresh.phtml) or by using javascript.
Edit: To redirect with javascript see How to redirect to another webpage in JavaScript/jQuery?