Antigravity Agent
6.1 KiB
6.1 KiB
id, title, category, status, source_trust_level, verification_status, created_at, updated_at, tags, tech_stack, applied_in, aliases
| id | title | category | status | source_trust_level | verification_status | created_at | updated_at | tags | tech_stack | applied_in | aliases | ||||||||||||||||||
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| backend-mqtt-iot | MQTT — IoT messaging protocol | Coding | draft | B | conceptual | 2026-05-09 | 2026-05-09 |
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MQTT (IoT)
IoT 의 표준 protocol. TCP 위 의 가벼운 pub/sub. QoS 0/1/2. Retained / last will. Mosquitto / EMQX / AWS IoT.
📖 핵심 개념
- Pub/sub via topic.
- Topic: hierarchical (
home/livingroom/temp). - QoS 0 (at most once), 1 (at least), 2 (exactly).
- Retained = 마지막 message 가 새 subscriber.
💻 코드 패턴
Connect (Node)
import mqtt from 'mqtt';
const client = mqtt.connect('mqtt://broker.hivemq.com', {
clientId: 'my-device-' + Math.random(),
username: 'user',
password: 'pw',
will: {
topic: 'devices/my-device/status',
payload: 'offline',
qos: 1,
retain: true,
},
});
client.on('connect', () => {
client.publish('devices/my-device/status', 'online', { qos: 1, retain: true });
client.subscribe('home/+/temp'); // wildcard
});
client.on('message', (topic, payload) => {
console.log(topic, payload.toString());
});
Topic wildcard
+ : single level (home/+/temp)
# : multi level (home/#)
home/livingroom/temp -> matches home/+/temp, home/#
home/kitchen/light/dim -> matches home/#
QoS
QoS 0: fire-and-forget (UDP-like).
QoS 1: at-least-once (ack 가 보장 — 중복 가능).
QoS 2: exactly-once (4-step handshake — 느린).
→ 대부분 QoS 1.
Sensor / 빈번 = QoS 0.
Critical = QoS 2.
Retained
client.publish('home/temp', '22.5', { retain: true });
// 새 subscriber 가 sub 즉시 = '22.5' 받음 (retained).
→ "현재 상태" 식.
Last will
const client = mqtt.connect(url, {
will: {
topic: 'devices/my-device/status',
payload: 'offline',
},
});
→ Client crash / disconnect = broker 가 자동 publish.
Clean session
mqtt.connect(url, { clean: false, clientId: 'persistent-id' });
→ Reconnect 시 missed message 받음 (broker 가 queue).
Broker
# Mosquitto (가장 popular open source)
docker run -p 1883:1883 eclipse-mosquitto
# EMQX (Erlang, 큰 scale)
docker run -p 1883:1883 -p 8083:8083 emqx/emqx
# HiveMQ (commercial / community)
MQTT over WebSocket
const client = mqtt.connect('ws://broker:8083/mqtt');
→ Browser-friendly (HTML5).
MQTT 5.0 features
- Reason code (relevant error).
- Topic alias (long topic 의 short).
- User properties (custom header).
- Shared subscription ($share/group/topic).
- Session expiry.
Shared subscription
client.subscribe('$share/group1/sensor/temp');
// → Group 1 의 1 subscriber 만 받음 (load balance).
→ N consumer 가 1 message 만.
vs HTTP
HTTP:
- Request-response.
- 큰 overhead (header).
- Stateless.
MQTT:
- Pub/sub.
- 작은 overhead (binary).
- Persistent connection.
→ IoT (작은 device, 매 정보 / 연속) = MQTT.
vs WebSocket
WebSocket: protocol layer.
MQTT-over-WebSocket: MQTT 의 message 위 WS.
→ MQTT 가 application protocol.
vs CoAP
CoAP: HTTP-like for IoT (UDP).
MQTT: TCP, pub/sub.
→ CoAP = constrained device.
MQTT = 일반.
AWS IoT Core
import { mqtt as awsmqtt } from 'aws-iot-device-sdk-v2';
const builder = awsmqtt.AwsIotMqttConnectionConfigBuilder.new_mtls_builder_from_path(
cert, key
);
builder.with_endpoint('xxx.iot.us-east-1.amazonaws.com');
const conn = new awsmqtt.MqttClient().new_connection(builder.build());
await conn.connect();
→ Managed broker. mTLS auth. Rules engine.
Message routing (broker level)
EMQX rule:
SELECT * FROM "sensor/+/temp" WHERE payload.value > 80
→ save to DB
→ alert webhook
→ Broker 가 자체 logic.
Sparkplug B
Industrial IoT spec.
- Birth / death message.
- Metric definition (DDATA / NDATA).
- Topic structure (spBv1.0/...).
→ 큰 industrial automation.
MQTT-SN (sensor network)
MQTT 의 UDP version.
- 매우 작은 device.
- Gateway 가 MQTT broker 와 bridge.
Security
- mTLS (인증).
- Username / password (간단).
- Token-based (modern).
- ACL (topic 별 read/write).
- Encryption in transit (TLS).
Use case
- Smart home (Home Assistant)
- Industrial IoT (Sparkplug)
- Connected car
- Asset tracking
- Sensor network (temperature, humidity)
- Real-time chat
- Game (state sync)
Production setup
HA (3+ broker, cluster).
Persistence (Redis / DB).
Auth (mTLS + token).
Monitoring (Prometheus).
TLS (Let's Encrypt).
Rate limit (per client).
함정
- QoS 2 가 default 가정: 느린.
- Retained 가 항상 사용: 메모리.
- Wildcard `#` 가 root: 모든 message.
- Auth 없음: 누구나 publish.
- ACL 없음: 누구나 모든 topic.
- Broker 1 instance: SPOF.
Telemetry pattern
Device → MQTT → Broker → Stream processor → DB / dashboard.
Example:
- ESP32 가 sensor reading.
- Broker (EMQX).
- Kafka bridge.
- TimescaleDB.
- Grafana.
Home Assistant
mqtt:
sensor:
- name: 'Temperature'
state_topic: 'home/livingroom/temp'
unit_of_measurement: '°C'
Cloud option
- AWS IoT Core
- Azure IoT Hub
- GCP IoT Core (deprecated)
- HiveMQ Cloud
- EMQ Cloud
- AdafruitIO (작은 hobby)
🤔 의사결정 기준
| 상황 | 추천 |
|---|---|
| IoT device | MQTT |
| 작은 / 간단 | Mosquitto |
| 큰 scale | EMQX / HiveMQ |
| AWS-native | IoT Core |
| Industrial | Sparkplug B |
| Web client | MQTT-over-WS |
| Constrained UDP | CoAP / MQTT-SN |
❌ 안티패턴
- HTTP poll IoT: 매우 비효율.
- QoS 2 always: 느린.
- No auth: 침해.
- No retained 이전 state: subscriber 가 모름.
#매 client: 폭발.- No HA broker: SPOF.
🤖 LLM 활용 힌트
- MQTT = IoT 의 표준.
- QoS 1 가 sweet spot.
- Retained + last will 가 핵심.
- EMQX / Mosquitto 가 default broker.