# HTTP

Application level protocol

Defines:

• message syntax
• types of messages exchanged
• message semantics

# Message Syntax

• base types
• flat types (array or structure)
• complex types (has pointers)

Conversion Strategy:

• Canonical Intermediate Form (send and rec side convert internal representation to agreed upon format)
• Receiver Makes Right (sender includes data about it's internal representation)

Tagging:

• untagged (agree on type, length, and location of data)
• tagged (include in message tags about the data) (json and protobuf)

start line
message header
message body

# Types

options
get
head
post
put
delete
trace
connect

# connection

• client initiate TCP connection
• client requests file

Versions:

1.0 first
1.1 persistent connections (no handshake per file)
2.0 multiplexed requests (requests objects in parallel)
3.0 HTTP over QUIC instead of TCP