rails 3.1 realtime update feature

I've seen many sites that their messages feed is keep sliding down incessantly. For example: the previous version of twitter and now the foursquare. How to do that?

Moreover, I also want to know 开发者_JS百科how to implement meetup's RSVP instant push in rails, they update it by seconds?

Thanks.

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These companies will most likely be using realtime web technologies. Here are a few you could use with a rails and/or ruby applications:

• http://juggernaut.rubyforge.org/
• http://faye.jcoglan.com/
• http://cramp.in/
• https://github.com/raggi/async_sinatra
• http://postrank-labs.github.com/goliath/

You could also use Pusher (who I work for) as we have a Pusher gem. If you do this it means you are not hosting the realtime infrastructure yourself.