Zenoh-MQTT Bridge - Cyberwave Docs

The Zenoh-MQTT bridge runs on edge devices alongside Edge Core. It connects the local high-performance Zenoh data bus (cyberwave.data) to the cloud MQTT broker, forwarding selected channels in both directions.

Overview

Direction	Source	Destination	Use case
Outbound	Zenoh channel	MQTT topic	Inference results, events, health to cloud
Inbound	MQTT topic	Zenoh channel	Workflow sync commands from cloud

When MQTT is disconnected, outbound messages are buffered to a persistent file-backed queue and drained in FIFO order on reconnect.

Quick start

from cyberwave.zenoh_mqtt import ZenohMqttBridge, BridgeConfig

bridge = ZenohMqttBridge(
    config=BridgeConfig(
        twin_uuids=["<twin_uuid>"],
        outbound_channels=["model_output", "event", "model_health"],
    ),
    mqtt_host="<mqtt_host>",
    mqtt_port=8883,
    mqtt_password="<api_key>",
)
bridge.start()

Default topic mapping

Zenoh key	MQTT topic	Direction
`cw/{twin}/data/model_output`	`cyberwave/twin/{twin}/model_output`	Edge to Cloud
`cw/{twin}/data/event`	`cyberwave/twin/{twin}/event`	Edge to Cloud
`cw/{twin}/data/model_health`	`cyberwave/twin/{twin}/model_health`	Edge to Cloud
—	`cyberwave/twin/{twin}/commands/sync_workflows`	Cloud to Edge

Offline queue

When the MQTT connection drops:

Outbound messages are appended to segmented files under CYBERWAVE_BRIDGE_QUEUE_DIR.
On reconnect, the queue is drained in FIFO order before resuming live forwarding.
Queue size is bounded by CYBERWAVE_BRIDGE_QUEUE_MAX_BYTES (default 50 MiB); oldest segments are evicted when the budget is exceeded.

Configuration

Environment variable	Default	Description
`CYBERWAVE_BRIDGE_ENABLED`	`false`	Master switch
`CYBERWAVE_BRIDGE_TWIN_UUIDS`	—	Comma-separated twin UUIDs
`CYBERWAVE_BRIDGE_OUTBOUND_CHANNELS`	`model_output,event,model_health`	Channels forwarded to MQTT
`CYBERWAVE_BRIDGE_INBOUND_TOPICS`	`commands/sync_workflows`	MQTT suffixes forwarded to Zenoh
`CYBERWAVE_BRIDGE_QUEUE_DIR`	`/tmp/cyberwave_bridge_queue`	Persistent queue directory
`CYBERWAVE_BRIDGE_QUEUE_MAX_BYTES`	`52428800`	Max offline queue size (bytes)
`CYBERWAVE_BRIDGE_MQTT_QOS`	`1`	MQTT QoS for bridge messages

Transition compatibility

Existing direct MQTT paths (cw.mqtt.publish(...)) continue to work unchanged. The bridge is additive — channels published via both Zenoh and MQTT are handled idempotently on the cloud side.