MQTT-SN gateway

The MQTT-SN stream gateway maps selected UDP protocol records into the common broker command ABI. It maintains a bounded, tenant-scoped Topic ID lifecycle and supports the selected MQTT-SN 1.2 profile.

Configuration surface

stream {
  server {
    listen 1884 udp;
    iot_gateway_mqttsn on;
    iot_gateway_mqttsn_gateway_id 1;
    iot_gateway_mqttsn_identity tenant-a gateway-a NGINZ_IOT_MQTTSN_PASSWORD;
    iot_gateway_mqttsn_max_payload 512;
    iot_gateway_mqttsn_topic_registry 16;
    iot_gateway_mqttsn_advertise 30s;
    iot_gateway_mqttsn_advertise_to 239.255.0.1:1884;
    iot_gateway_mqttsn_sleep_max 3600;
    iot_gateway_mqttsn_iotd on;
    iot_gateway_mqttsn_iotd_rings /nginz-iot-edge 4096 1024 1024 1 1;
  }
}

Selected behavior

The current boundary covers CONNECT, REGISTER, PUBLISH, SUBSCRIBE, UNSUBSCRIBE, PUBACK, PINGREQ, and DISCONNECT command shaping. A bounded 32-entry, 60-second table correlates asynchronous PUBACK, SUBACK, and UNSUBACK responses by kind and message ID, including out-of-order delivery. Capacity, payload, sleep, and ring limits are mandatory operational controls.

When advertisements are enabled, advertise_to must be an explicit IPv4 broadcast or multicast destination. Worker slot 0 owns a process-local nginx timer and UDP socket; workers share no advertiser state, and a graceful reload may briefly duplicate an idempotent ADVERTISE packet.

The selected MQTT-SN 1.2 profile passed its complete 17-scenario matrix on both installed image variants against pinned Paho peers. Advertise, sleeping-client, and QoS 2 MQTT-SN behaviors outside that profile remain excluded.