As with pipelining, I think this would be better handled at the HTTP level than the XHR API level. We could define response headers for a server to indicate that it allows more than two connections per client, or alternately that a specific connection should not count towards the limit.
I don't have a big problem with this being defined by headers, that seems reasonable. It is worth noting that doesn't achieve quite the same effect as doing it in XHR since there is time elapsed between the time the request is made and the response headers are received. If two connections are currently servicing responses, and third connection wishes to declare itself as an extra connection, from the client side this could be delivered immediately, but with header based permission, it would have to wait it's turn. That being said, I don't think these are terrible issues, and a fixing it at the HTTP level is fine with me. Kris
