HTTP/1.x messages 缺點
HTTP/1.x messages have a few drawbacks for performance:
- Headers, unlike bodies, are uncompressed.
- Headers are often very similar from one message to the next one, yet still repeated across connections.
- No multiplexing can be done. Several connections need opening on the same server: and warm TCP connections are more efficient than cold ones.
HTTP/2 Frames
HTTP/2 introduces an extra step: it divides HTTP/1.x messages into frames which are embedded in a stream. Data and header frames are separated, this allows header compression. Several streams can be combined together, a process called multiplexing, allowing more efficient underlying TCP connections.
Binary_framing2.png
