Long polling via nginx proxy


hi all,
i am using nginx (as a proxy load balancer) in front of my servers for
a long polling application. in the configuration documentation for the
proxy module it says

“For Comet aplications based on long-polling it is important to set
proxy_buffering to off, otherwise the asynchronous response is
buffered and the Comet does not work.”

can anyone please explain this further?

also, my nginx handles ssl connections. considering that a typical
sessions lasts for about 30 minutes, and the default value for the
‘ssl_session_timeout’ is 5m, how does this affect a session? what
would be a good value for this directive for a long polling based