Duplex, simplex, half-duplex?
Duplex : two-way transmission can be carried out simultaneously. Example: Broadcast
Simplex : only support data transmission to transmit data in one direction, while only one can send or receive information. Example: walkie-talkie
Half duplex : data transmission permission to transmit data in both directions, but at any one time, allowing data to propagate only in one direction, it is actually a simplex communication switching direction; the same time, there may be only one of receiving or transmitting information. Examples: phone calls
What is HTTP protocol model?
- Http original version is 1.1 or less is simplex.
- Version 1.1 can be achieved by half-duplex kepp alive long it normally takes to open the server configuration connection. Now with version 1.1 of the site, but need to see a long connection is available to configure the server.
- Http2.0 version http generation is now in trial in many browsers and servers do not support, is insufficient to make up for prior agreement duplex communication.
- http protocol has multiple versions, there are differences, as of 2019.1, the mainstream protocol is http1.1
- http1.1 following versions, http connections for short connections, tcp connection to send messages waiting to receive information after disconnection.
- http1.1 is half-duplex, long established connections, multiplexing occurs, can have multiple http requests sent without waiting for a reply, but a reply to a reply sequence. (mainstream)
- http2.0 is full duplex, without waiting after receiving a message, the second message may be sent directly.