When I say don't use js, I meant don't use js alone, because it doesn't have the right tools to create an instant messaging app.
I didn't tell him to use websockets. I said that if he wanted to use js, then use js websockets. But to be cautioned because cross browser compatibility is not very well with js web sockets...
He can not use nodejs unless he has his own server we are looking for a client side + php solution. And flash is used for a lot more than web games. In fact most js chat providers use flash communicating with js... So they don't have to poll their server using up all of their resources. ;)
Besides there arent that many options for listening to websockets that require using something that is most likely already installed on the persons computer AS an add on to their browser.
So a few to choose from are Flash, Java, JS WebSocket, SilverLight(Windows Only, I think? I don't even believe that many windows computers have this installed.) Anyone care to add to the list of languages that don't require an additional installation for the client side user?
P.S. !Angel... Why would you say to never use flash then suggest Socket.IO when Socket.IO uses flash?