IoT and MQTT#

Tina4 includes a zero-dependency MQTT 3.1.1 client for telemetry, device state, asset tracking, and EV charging. It connects to an external broker such as Mosquitto, EMQX, HiveMQ, or AWS IoT. Tina4 is not a broker.

Configure and publish#

TINA4_MQTT_URL=mqtt://127.0.0.1:1883TINA4_MQTT_CLIENT_ID=warehouse-apiTINA4_MQTT_KEEPALIVE=60TINA4_MQTT_TLS_VERIFY=trueTINA4_MQTT_CA_FILE=/run/secrets/mqtt-ca.pem

Use mqtt:// or tcp:// for plain TCP and mqtts:// for TLS. Put credentials in URL user information or constructor arguments. There are no username or password environment variables.

mqtt = Tina4::Mqtt.newpacket_id = mqtt.publish(  "fleet/meter-42/telemetry",  '{"kwh":12.5}',  qos: 1)mqtt.disconnect

Construction connects by default. QoS 0 waits for no acknowledgement. QoS 1 returns the packet id after PUBACK. Tina4 refuses QoS 2.

mqtt = Tina4::Mqtt.new(clean_session: false)mqtt.consume("fleet/+/telemetry", qos: 1) do |message|  process(message.topic, message.to_s)end

consume acknowledges after successful block handling. Use receive(ack: false) followed by message.acknowledge for manual control. Messages expose topic, byte payload, QoS, packet id, retained and duplicate flags, acknowledgement, text through to_s, and to_h.

Retained publishes store current state; an empty retained payload clears it. Configure will_topic, will_payload, will_qos, and will_retain for an unclean disconnect. disconnect suppresses the will; kill lets the broker publish it. TLS verification defaults to true. tls?, cipher, and tls_version report the connection. One client has one socket reader.