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