Turning MQTT v5 inside out
summary
Protocol changes in MQTT v5 are concrete not rhetorical: topic aliases cut repeated-topic overhead (example: first message ~74 bytes then subsequent messages ~11 bytes), properties live in a length-prefixed tail so unused messages cost one byte, maximum packet size lets constrained clients tell brokers to skip oversized retained messages instead of disconnecting, an authentication command enables bidirectional multi-step auth, and reason codes give explicit error signals. Implementations lag (only a few servers plus Paho test tools and some C client work), and transport still requires ordered lossless bidi links so UDP is out.
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chapters (15)
- 0:00Introduction
- 0:35What is MQTT
- 1:12Why use MQTT
- 2:20What specifies MQTT
- 3:40Lightweight
- 5:38Summary
- 6:23Brief
- 7:07Properties
- 9:14Subscriptions
- 10:19Embedded
- 11:28Topic aliases
- 13:11Authentication and authorization
- 15:13Error handling
- 17:32MQTT downsides
- 21:55MQTT as a local connection
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