Our application is currently only a "regular" web app, with no fancy things like streaming HTTP or websockets. It's mostly a Rails app, served by a few (20 on 2 machines) Unicorn workers, proxied by a venerable nginx server which deals with load balancing.

This has been working quite well for the past year and the app now serves between 400 and 800 requests per second at any point during the day.

We're soon releasing 2 new APIs, which are both served by a Node application : a websocket one, as well as a long polling HTTP one. (the fancy thing like the Twitter streaming API where HTTP connections never end). They both use the same port on node and since the node app is stateless, we can certainly deploy a few of them to handle the traffic.

The app (node) is now deployed in 5 instances and are now listening on 5 different 'private' ports on the same host. We need to put something in front of them to load balance, but also something that is able to deal with sockets (either websocket or HTTP streaming) which are intended to stay 'up' for days.

The question is then : what? I read somewhere that HAProxy does a better job than Nginx at this. What do you recommend?