MQTT topics and messages¶

All topics have the form idryer/{serial}/{suffix}, where {serial} is the device serial number.

This document describes the topics and commands implemented by MqttClient from idryer-core. The full platform interface (all backend commands for all device types) is in contracts/portal_backend_status.md.

Device → backend¶

info¶

idryer/{serial}/info    retained=true    publish QoS=0

Published once when the device first goes Online, and again on receiving a ping command.

The payload is defined by the product via IProfile::buildInfoJson(). Fields expected by the backend at a minimum: hardwareVersion, firmwareVersion, timestamp.

Example for Storage Link:

{
  "deviceType": "storage_link",
  "firmwareVersion": "1.0.0",
  "hardwareVersion": "1.0",
  "timestamp": "2026-04-28T10:00:00Z"
}

telemetry¶

idryer/{serial}/telemetry    retained=false    interval ~10 s

Published by the product via pub.publishTelemetry(). The library does not publish automatically.

Example for Storage Link (climate sensor):

{
  "units": [
    {"unitId": "U1", "temperature": 23.5, "humidity": 47.2}
  ]
}

status¶

idryer/{serial}/status    retained=true    published on change

Published by the product on state change via pub.publishStatus(). Payload is defined by the product.

config¶

idryer/{serial}/config    retained=false    on request

Published on receipt of device.getConfig (invoke) or in response to get_config. Called via pub.publishConfig() or pub.publishConfigRaw().

For large payloads (> 16000 bytes), published in chunks: each chunk contains tid, idx, total, last, d.

config/delta¶

idryer/{serial}/config/delta    retained=false    on change

Partial config update via pub.publishConfigDelta(). The backend expects a d field (an object with the changes).

events¶

idryer/{serial}/events    retained=false    on event

Published by the product via pub.publishEvent(). The library does not generate events automatically.

integrations/status¶

idryer/{serial}/integrations/status    retained=true    on change

Published by LinkIntegrationsManager. Contains the active integration connection state.

offline (LWT)¶

idryer/{serial}/offline    retained=false    on unexpected disconnect

Set by the broker automatically when the TCP connection drops. The device never publishes this topic manually.

Backend → device¶

The device subscribes to idryer/{serial}/commands/#.

commands/ping¶

idryer/{serial}/commands/ping

Handled directly by IdryerRuntime — syncs system time via settimeofday() and re-publishes info.

{"timestamp": "2026-04-28T10:00:00Z"}

commands/invoke¶

idryer/{serial}/commands/invoke

Preferred path for product actions. The library passes the command to the product's CommandHandler (recommended path). If no CommandHandler is registered, the command falls through to the built-in ActionDispatcher (fallback).

{"action": "led.pulse", "args": {"color": "FF0000", "duration": 500}}

The built-in action device.getConfig is handled by the runtime or the product handler — calls IProfile::getConfig() and publishes the result.

commands/set¶

idryer/{serial}/commands/set

Sets a single configuration parameter. Passed to the product's CommandHandler (recommended path). Fallback — built-in ActionDispatcher::handleSet() if no CommandHandler is registered.

{"id": 3, "val": 55}

commands/link_integration¶

idryer/{serial}/commands/link_integration

Integration management. Handled by LinkIntegrationsManager via the product's CommandHandler.

{"type": "bambu", "enabled": true, "ip": "192.168.1.50", "serial": "...", "lanAccessCode": "..."}

commands/bambu_apply¶

idryer/{serial}/commands/bambu_apply

Apply filament parameters to an AMS slot on a Bambu printer. Handled by LinkIntegrationsManager.

Other platform commands¶

Commands drying, storage, profile, stop, get_config, read_rfid, write_rfid, and others are part of the full iDryer platform interface. They are not handled by idryer-core directly; they are delivered to the product's CommandHandler. Reference: contracts/portal_backend_status.md.

Topic format¶

// Topic construction
idryer_make_topic(buf, sizeof(buf), serialNumber, "telemetry");
// → "idryer/DEVICE_AABBCCDDEEFF/telemetry"

Suffix constants are defined in mqtt/idryer_topics.h:

#define IDRYER_TOPIC_INFO               "info"
#define IDRYER_TOPIC_TELEMETRY          "telemetry"
#define IDRYER_TOPIC_STATUS             "status"
#define IDRYER_TOPIC_CONFIG             "config"
#define IDRYER_TOPIC_CONFIG_DELTA       "config/delta"
#define IDRYER_TOPIC_EVENTS             "events"
#define IDRYER_TOPIC_OFFLINE            "offline"
#define IDRYER_TOPIC_INTEGRATIONS_STATUS "integrations/status"
#define IDRYER_TOPIC_CMD_WILDCARD       "commands/#"