[1] RFC 6202 - Known Issues and Best Practices for the Use of Long Polling and Streaming in Bidirectional HTTP ( ( 版)) <http://tools.ietf.org/html/rfc6202#section-1>
[2] RFC 6202 - Known Issues and Best Practices for the Use of Long Polling and Streaming in Bidirectional HTTP ( 版) <http://tools.ietf.org/html/rfc6202>
HTTP Long Polling: The server attempts to "hold open" (not
immediately reply to) each HTTP request, responding only when
there are events to deliver. In this way, there is always a
pending request to which the server can reply for the purpose of
delivering events as they occur, thereby minimizing the latency in
message delivery.