- FIG request in a first embodiment, a single transmission request is a request, and then receive the response request once, the display is very inefficient.
- Thus http1.1 proposed pipelined (PIPELINING) technology , it is requested as shown in the second embodiment, one transmission request multiple requests.
- However pipelining, also according to the order must be received at the time of receiving the response is returned, if a request is met before the obstruction, even if the latter request has been processed, the requests still need to wait for obstruction processed. This situation is shown in the third, after the first request is blocked, subsequent requests need to wait, which is the head of line blocking (Head of line blocking).
- In order to solve the blocking problem, http2 proposed multiplexed (Multiplexing) technology, Multiplexing is professional terms in the field of communications and computer networks. http2 of multiple requests with a tcp multiplexed link , a TCP connection is divided into several streams (Stream), each stream may be transmitted several messages (the Message), each message by a number of the smallest binary frame (Frame )composition. I.e. each request-response for fine resolution binary frame Frame, so that even if a request is blocked, it will not affect the other requests, the fourth case shown in FIG.
QUIC
- Are based on the case of TCP the above said, because TCP is a reliable transport protocol, a plurality of requests if there is a TCP connection request packet loss, then it will perform retransmission. The Google proposed QUIC (Quick Internet Connections UDP), is based on an experimental fast transport protocol of the UDP + Http2, UDP datagram oriented, so the situation will not encounter packet loss retransmission, thereby further reducing network latency, head of line blocking to solve the problem.
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