A Quick Reference To HTTP

HTTP 0.9 Protocol:

• Defined in 1991
• Latency is not at all a factor in HTTP 0.9
• In order to perform an http request client has to open a new TCP connection which is closed by server after responding to it.
• HTTP 0.9 User 3 way hand shake mechanism to establish a connection
• Its s simple text based protocol
• Only GET Method is allowed and Response Is HTML
• No Headers and Status Codes
• Invented by Tim Berners-lee at CERN
• Need a TCP connection for each Request

TCP 3 way Handshake:

HTTP 0.9 using telnet

HTTP 1.0 Protocol:

• Introduced in 1996
• HEAD and POST Methods were added
• Concept of header fields are introduced
• User-Agent introduced in Request (for debugging purpose)
• Content-Length introduced in Response (to identify the proper response)
• Caching , Authorization etc
• Still it Needs a TCP connection for each Request
• Status Codes are introduced
• Non-HTML can also be transmitted over this protocol

Telnet Using HTTP 1.0:

HTTP 1.1 Protocol:

• Published om 1997
• Persistent Connection Introduced
• The same connection can be used for consecutive request for single embedded documents like images etc.
• Chunked Responses were supported
• HOST header has been introduced. This allowed hosting different domains from same IP address
• Content Negotiation, encoding and type are introduced.
• GET, HEAD, POST, PUT, DELETE, TRACE, OPTIONS

Telnet Using HTTP 1.1

Keep-alive Header:

 This header allowed the connection to be opened for some time

Keep-Alive: timeout=600,max100

Connection: Keep-Alive

 

Telnet Using Keep Alive HTTP 1.1

HTTP/2 protocol:

• Started in 2015
• Http2 is a binary, multiplexed, network protocol
• Frames and streams are used to communicate using this protocol
• Frames are exchanged over TCP connection instead of text based messages. The following frame types are available.
• HEADERS, DATA,SETTINGS, or GOAWAY are different frame types.

There are two ways to use http2 protocol

1. Using upgrade header
   1. Send an http connection with upgrade header

GET /index.html HTTP/1.1

Host: server.example.com

Connection: Upgrade, HTTP2-Settings

Upgrade: h2c

HTTP2-Settings: <base64url encoding of HTTP/2 SETTINGS payload>

1. Http 2 compatible server will accept the connection with switching protocols.

HTTP/1.1 101 Switching Protocols

Connection: Upgrade

Upgrade: h2c

[ HTTP/2 connection …

ALPN: Application level Protocol Negotiation:

ALPN allows a TLS connection to negotiate which application level will be running across it.

After establishing an HTTP/2 connection each endpoint has to send a connection preferences as a final confirmation and to establish the initial settings for http2 connection.

CURL Using HTTP 2.0

Here is the code rut a jetty server with http2 protocol

https://github.com/prabhukvn/springboot-jetty-http2

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