Strategies

HTTP/1.1

  • Message delimitation is done via headers and content length.

  • Server and client use the Content-Length  field to specify the exact size of the message body. This field tells the receiver how many bytes to read for the message.

  • If the message size is not known in advance the server can use chunked transfer encoding, where data is split into variable-sized chunks and each chunk is prefixed with its size in hexadecimal.

  • In the header: 

Content-Length: 1234

HTTP/2.0

  • Introduces stream multiplexing which means multiple messages can be sent at the same time using the same channel.

  • HTTP/2 uses frames to send data pieces. Each frame has a header with information about the data type and payload size.

  • Each message is associated with a Stream ID which allows multiple requests/responses to flow concurrently without interfering with each other.

  • Head of Line Blocking: In HTTP/2 requests/responses are split into frames and frames from different requests can be sent simultaneously.

HTTP/3.0 (QUIC)

  • HTTP/3 is an evolution of HTTP/2 built on the QUIC protocol, developed to improve performance and reduce latency.

  • QUIC replaces TCP with UDP to provide greater agility and uses frames to send data packets. Messages are split into frames and QUIC handles multiplexing of these messages.

  • HTTP/3 does not depend on the Content-Length  header. Instead QUIC splits data into small packets and sends them independently, controlling flow via multiplexed data streams.

  • Data Frames: QUIC uses data frames and each frame contains the payload size and a Stream ID that lets the server organize messages correctly.