[mike_hearn]

Good MQ libraries know how to do backoff and retry transparently, so if you aren't provisioned for peak load (which is what melting implies) you can just reject connections for a while until everyone is back.

The alternative with polling rapidly turns into being melted all the time - it's literally handling constant reconnection load - especially as you don't control the polling code and as the user is expected to write it themselves you can safely bet it will be MVP. Retries if they occur at all will be in a tight loop.

I worked on Gmail for a few years and we had a ton of clients permanently connected for IMAP, web long polling and Talk. Those clients tended to be well written and it wasn't the big problem people seem to think it is, especially as some could do client side LB which reduced resource requirements server side. I also experienced (luckily from a distance) fully HTTP polling based systems where backoff/retry wasn't implemented properly and caused services to go hard down because they couldn't handle being hit with all the polling simultaneously, and the clients just broke or did something stupid like immediately retry if they got server errors.

Fundamentally, state is fundamental and can't be removed, so it's going to be sitting somewhere. If state isn't in the protocol stack then it's in your database or session cache instead. Sometimes that's better, sometimes it's worse.