As it is evident that AJAX based chats do not scale, so what would you use for chats? Custom servers? Or any other methods?
Since with Rails each chat connection will take lots of memory, it won't be feasible to even have Rails run for each message. What do you recommend for use here?
I also tried to implement a sample chat app with AJAX (in built Ajax.updater) but it didn't workout. I'm sure there might be some good ajax solution.
But since this is based on server push technology, try Juggernaut (http://juggernaut.rubyforge.org/). I personally haven't tried, but it seems like it's good.
Or else consider web sockets (in HTML5) if possible.