Yeah, you could have multiple requests hanging open with the server to enable faster server sends (and if a client wants to send data rapidly it could make mult

Yeah, you could have multiple requests hanging open with the server to enable faster server sends (and if a client wants to send data rapidly it could make multiple parallel POST requests). The downside is you end up with a complex stateful protocol, with multiple sockets, and need the ability to handle out-of-order data. If you're targeting a platform that can't do HTTP streaming, then sure, but otherwise this is a pretty gnarly road to go down. My personal preference for long-polling is to use it for stateless / RESTful APIs that have infrequent updates. Super clean, easy to use from the client's perspective, and efficient enough. I would not use it for stateful communication (IMO SockJS and Engine.IO are gross but I understand why they exist).