Webbased chat in php without using database or file

Question

I am trying to implement a realtime chat application using PHP . Is it possible to do it without using a persistent data storage like database or file . Basically what I need is

Answer 1

If You need to use just PHP, then You can store chat messages in session variables, session could be like object, storing a lot of information. If You can use jQuery then You could just append paragraph to a div after message has been sent, but then if site is refreshed, messages will be gone. Or combining, store messages in session and update that with jQuery and ajax.