<https://www.phpclasses.org/blog/package/3213/post/1-Tutorial-on-Creating-an-AJAX-based-Chat-system-in-PHP.html>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://jeffn.users.phpclasses.org/blog/package/3213/post/1-Tutorial-on-Creating-an-AJAX-based-Chat-system-in-PHP.html>