respond partial content

Hi.

This may seem like an absurd request. However it is becausy I
integrate with a legacy system.

I am in the need to respond partial content (flush) before the action
is fully complete. This should prevent the legacy system to timeout.

I need to send HTTP headers and some content (to indicate to the
client that my rails app is actually alive), and the at the end of the
action to complete and close the connection.

Something like this

def index
  respond_headers
  do_something_that_takes_a_long_time #more than a minute
  render :text => 'DONE'
end

Does anybody know how to do this?

Jarl