====== MQTT ======

MQTT (Message Queuing Telemetry Transport) is a lightweight publish/subscribe messaging protocol designed for low-bandwidth, high-latency, or unreliable networks.

===== Purpose in AOFS =====

  * Sensor telemetry transmission
  * Event and alert messaging
  * Field → Farm Controller aggregation
  * Optional Farm → HQ synchronization

===== Layer Mapping =====

  * Field Controller → Farm Controller
  * Farm Controller → HQ / Federated Layer
  * Optional local broker within farm LAN

===== Strengths =====

  * Low bandwidth usage
  * Works well over unstable connections
  * Supports retained messages and QoS levels
  * Simple implementation on embedded controllers (e.g., ESP32)

===== AOFS Compliance Notes =====

  * MQTT must not be used to bypass Field Controller safety logic
  * Loss of MQTT connectivity must not interrupt irrigation safety functions
  * All received remote commands must be validated locally
  * All transmitted and received events must be logged