HTTP versions
1.0
1995 – had to establish a new connection for every request and the connection would close after it. So if a webpage had 4 images so 5 requests need to be established including for 1 for the html page.
This is TCP slow start.
1.1
1995 – Till 2015 – had introduced a keep alive header so connection once established would continue for a certain period.This way it was more speedy. (persistent connections)
It also introduced Options header to know HTTP servers ability.
Compression
Chunked transfer – response was sent for dynamic pages before its actual size was known
Multiple domains from one IP address – helped in saving address space
2
Multiplexing Streams -Multiple streams in One TCP connection . Instead of TCP the flow is controlled by server and client instead of TCP. So the ordering which images to load first and later can be decided. So the perceived improved performance
Server Push – if we load a HTML page and it requires additional resources like CSS etc to load it can be sent by the server itself to improve the performance.
Compression – improvised. The header size is reduced as it is compressed.
3
Still experimental. Developed by google. Makes use UDP with congestion control instead of TCP.
No Cache –