Post 10: HTTP/2: Multiplexing, HPACK & Server Push

[honeycoder96]

Epic: #15
Block: 6 — HTTP
Series order: 10 of 18

Description

The 2015 redesign of HTTP that solved head-of-line blocking at the application layer — introducing binary framing, stream multiplexing, and header compression.

Key topics

• Why HTTP/1.1 needed a redesign: HOL blocking, header verbosity, no prioritisation
• Binary framing layer: HTTP/2 messages as frames, not text
• Streams, messages, and frames: the three-level hierarchy
• Multiplexing: many concurrent logical streams over a single TCP connection
• Stream prioritisation and dependency trees
• HPACK header compression: static table, dynamic table, Huffman encoding — why headers went from ~800 bytes to ~50 bytes
• Server Push: proactively sending resources the browser hasn't asked for yet
• The remaining problem HTTP/2 didn't solve: TCP-level HOL blocking (motivation for HTTP/3)