Throttle

Throttle messages control channel runtime state (start/stop) for a specific channel on a node.

<node>/throttle/<code>/<channel>

Examples:

45fe/throttle/tlc.groups/live      # start/stop live signal group channel
45fe/throttle/traffic.volume/5s    # start/stop 5s traffic channel

For single-channel statuses, the channel name can be omitted:

45fe/throttle/tlc.plan

Payload:

{"action": "start" | "stop"}

Rules:

• The payload MUST include the key action.
• action MUST be one of: start, stop.

MQTT Behavior

• QoS: 1
• Retain: false

Throttle commands trigger channel state updates on corresponding channel topics:

<node>/channel/<code>/<channel>

Behavior

To receive status data, the channel must be running and the consumer must be subscribed to the associated status topic path.

Starting a channel causes the node to begin publishing data to the broker, even if no consumers are yet subscribed:

graph LR
A[Service] -->|.../tlc.groups/live| Broker

Consumers subscribe to the status topic path to receive data from the broker:

graph LR
A[Service] -->|.../tlc.groups/live| Broker
Broker -->|.../tlc.groups/live| B[Manager]

Stopping a channel causes the node to stop publishing. Consumers will no longer receive data even if they remain subscribed. The node publishes an empty retained message to clear stale data from the broker.

When a node connects, it MUST republish the current channel state for all configured channels to their <node>/channel/<code>/<channel> topics, so supervisors can recover state immediately from retained messages.