📡 IoT Engineering — MQTT, CoAP, LwM2M & Communication Protocols

Vault punya edge-computing-iot-security-architecture yang fokus ke security arsitektur IoT, dan embedded-systems untuk sistem embedded secara umum. Tapi belum ada yang bedah communication protocols yang menjadi tulang punggung IoT: bagaimana device dengan resource terbatas (baterai, CPU, bandwidth) bisa berkomunikasi secara efisien dan reliable. Catatan ini mencakup MQTT, CoAP, LwM2M, LPWAN, mesh protocols, dan serialization — dari teori sampai implementasi.

Posisi di Vault

Ini adalah protocol layer IoT yang melengkapi edge-computing-iot-security-architecture (security) dan embedded-systems (hardware). Juga terhubung dengan networking-fundamentals-tcpip-bgp (network layer), api-protocols-deepdive (API protocols secara umum), dan wireless-security-deepdive (wireless security).

Daftar Isi

1. IoT Architecture Overview
2. MQTT — Message Queue Telemetry Transport
3. CoAP — Constrained Application Protocol
4. LwM2M — Lightweight Machine to Machine
5. LPWAN — LoRaWAN, NB-IoT, LTE-M
6. Mesh Protocols — Zigbee, Z-Wave, Thread, Matter
7. Serialization — CBOR, Protobuf, MessagePack
8. Security — DTLS, OSCORE, Secure Boot
🔗 Koneksi ke Catatan Lain
✅ Checklist
Roadmap Belajar

1. IoT Architecture Overview

1.1 Four-Layer Architecture

┌──────────────────────────────────────────────────┐
│  APPLICATION LAYER                                │
│  Data analytics, dashboard, ML inference          │
├──────────────────────────────────────────────────┤
│  MIDDLEWARE LAYER                                 │
│  Message broker, device registry, rule engine     │
├──────────────────────────────────────────────────┤
│  NETWORK / PROTOCOL LAYER                         │
│  MQTT, CoAP, HTTP, LwM2M, LoRaWAN                │
├──────────────────────────────────────────────────┤
│  PERCEPTION / DEVICE LAYER                        │
│  Sensors, actuators, microcontroller, radio       │
└──────────────────────────────────────────────────┘

1.2 IoT Protocol Stack vs Internet Stack

Layer	Internet Stack	IoT Stack
Application	HTTP, WebSocket	MQTT, CoAP, LwM2M, gRPC
Transport	TCP, UDP	TCP, UDP, QUIC
Network	IPv4, IPv6	IPv6, 6LoWPAN, RPL
Link	Ethernet, Wi-Fi	LoRa, NB-IoT, BLE, Zigbee
Physical	Copper, Fiber	RF 868/915MHz, 2.4GHz, Sub-GHz

1.3 Protocol Selection Matrix

Protocol	Transport	Model	QoS	Overhead	Power	Use Case
MQTT	TCP	Pub/Sub	3 levels	Minimal	Medium	Sensor telemetry, push notif
CoAP	UDP	Req/Response + Observe	Confirmable	Minimal	Low	Constrained device REST
HTTP/2	TCP	Req/Response	Stream priority	Tinggi	High	Gateway-to-cloud
gRPC	HTTP/2	Streaming	Bidirectional	Sedang	High	High-throughput IoT
WebSocket	TCP	Full-duplex	None	Sedang	High	Real-time UI

2. MQTT — Message Queue Telemetry Transport

2.1 MQTT Architecture

┌────────┐    ┌──────────┐    ┌────────┐
│Publisher│───→│  Broker  │───→│Subscriber│
│(sensor) │    │ (Mosquitto) │    │ (app)   │
└────────┘    └──────────┘    └────────┘
                   │
              ┌────▼────┐
              │Subscriber│
              │ (logger) │
              └─────────┘

MQTT menggunakan publish/subscribe pattern — publisher gak tahu siapa subscriber, subscriber gak tahu siapa publisher. Semua routing dilakukan oleh broker berdasarkan topic hierarchy.

2.2 Topic & Wildcard

Topic: home/kitchen/temperature
         ↑     ↑       ↑
      domain  room  measurement
 
Wildcards:
  + (single level):  home/+/temperature  → home/kitchen/temperature, home/bedroom/temperature
  # (multi level):   home/#              → home/kitchen/temperature, home/garage/door/status
 
Example topics:
  sensor/temperature/room-01
  sensor/humidity/room-01
  actuator/light/room-01/set     ← command topic
  actuator/light/room-01/status  ← status response
  system/alert/+                  ← all alert topics

2.3 QoS Levels

QoS	Delivery Guarantee	Packet	Use Case
0	At most once	PUBLISH (fire & forget)	Sensor read non-kritis (temp)
1	At least once	PUBLISH + PUBACK	Must deliver, duplicate OK
2	Exactly once	PUBLISH + PUBREC + PUBREL + PUBCOMP	Payment, critical command

# QoS impact on throughput (test with Mosquitto)
mosquitto_pub -t test -m "hello" -q 0  # ~50,000 msg/sec
mosquitto_pub -t test -m "hello" -q 1  # ~15,000 msg/sec
mosquitto_pub -t test -m "hello" -q 2  # ~5,000 msg/sec

2.4 MQTT 5.0 Improvements

Feature	MQTT 3.1.1	MQTT 5.0
Session expiry	Clean session only	Session expiry interval
Reason codes	None	Full reason codes in ACK
User properties	None	Custom metadata in header
Topic alias	None	Reduce topic size
Flow control	None	Receive maximum
Server disconnect reason	None	Reason string

2.5 MQTT Broker Comparison

Broker	Language	Max Connections	Clustering	Protocols
Mosquitto	C	~100K	❌	MQTT 5.0, WebSocket
EMQX	Erlang	10M+	✅ Native	MQTT, CoAP, WebSocket, Stomp
VerneMQ	Erlang	~1M	✅ Native	MQTT 3.1.1/5.0
NanoMQ	C	~1M	✅ via EMQX	MQTT 5.0, ZeroMQ, WebSocket
HiveMQ	Java	~500K	✅	MQTT 5.0, Sparkplug

2.6 Practical MQTT with ESP32

// ESP32 + MQTT — sensor publish
#include <WiFi.h>
#include <PubSubClient.h>
 
WiFiClient espClient;
PubSubClient client(espClient);
 
void setup() {
    client.setServer("mqtt.example.com", 1883);
    client.setCallback(callback);
}
 
void loop() {
    if (!client.connected()) reconnect();
    client.loop();
 
    float temp = readTemperature();
    char msg[50];
    snprintf(msg, 50, "{"temp": %.2f, "hum": %.2f}", temp, readHumidity());
 
    // QoS 1 — at least once, sufficient for sensor data
    client.publish("sensor/temperature/living-room", msg, true);  // retain = true
    delay(30000);  // report every 30s
}

3. CoAP — Constrained Application Protocol

3.1 CoAP vs HTTP

CoAP adalah REST-like protocol untuk constrained device — mirip HTTP tapi di atas UDP, dengan overhead minimal.

HTTP:  GET /temperature → TCP + TLS → Header ~800 bytes
CoAP: GET /temperature → UDP + DTLS → Header ~4 bytes

CoAP Message Format:
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 ├─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤─┤
 │Ver│T│  TKL  │      Code     │          Message ID             │
 ├─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┼─┤
 │   Token (if any, TKL bytes) ...                                │
 ├─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┤
 │   Options (if any) ...                                         │
 ├─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┤
 │1 1 1 1 1 1 1 1│    Payload (if any) ...                       │
 └───────────────────────────────────────────────────────────────┘

3.2 CoAP Methods vs HTTP

HTTP	CoAP	Behavior
GET	GET	Retrieve resource
POST	POST	Create/update
PUT	PUT	Update resource
DELETE	DELETE	Delete resource
-	OBSERVE	Subscribe to resource changes
-	FETCH	Retrieve with request body
-	PATCH	Partial update

3.3 Confirmable vs Non-Confirmable

CON (Confirmable):
  Request → ACK timeout → retransmit (max 4×)
  Exponential backoff: 2s, 4s, 8s, 16s
  → Reliable delivery, but higher latency
 
NON (Non-Confirmable):
  Fire-and-forget — no ACK expected
  → Unreliable, but low latency & power
 
RST (Reset):
  Receiver doesn't understand message → sender stop retransmit

3.4 Observe Pattern (CoAP Subscription)

Client                                  Server
  │                                       │
  ├──── GET /temperature (Observe=0) ────→│
  │←──── 2.05 Content (token=0x42) ─────┤
  │                                       │
  │         (temperature changes)         │
  │←──── 2.05 Content (token=0x42) ─────┤
  │                                       │
  │         (another change)              │
  │←──── 2.05 Content (token=0x42) ─────┤
  │                                       │
  ├──── GET /temperature (Observe=1) ────→│  ← cancel observation
  │←──── 2.05 Content                     │

4. LwM2M — Lightweight Machine to Machine

4.1 LwM2M Architecture

LwM2M adalah protocol device management di atas CoAP — bukan cuma komunikasi data, tapi juga remote management:

┌──────────────────┐      CoAP/DTLS       ┌──────────────────┐
│   LwM2M Client   │◄───────────────────►│  LwM2M Server    │
│   (sensor, mote) │                      │  (cloud/backend) │
└──────────────────┘                      └──────────────────┘
       ▲                                         ▲
       │ Bootstrap                               │
       ▼                                         ▼
┌──────────────────┐                      ┌──────────────────┐
│ Bootstrap Server │                      │  Smartphone App  │
└──────────────────┘                      └──────────────────┘

4.2 LwM2M Interfaces

Interface	Fungsi	Contoh
Bootstrap	Initial config (server URL, credentials)	First-time device setup
Device Registration	Register ke LwM2M server	`Register /rd`
Device Management & Service Enablement	Read/Write/Execute resources	Reboot, firmware update
Information Reporting	Observe resource changes	Sensor value notification

4.3 Object/Resource Model

LwM2M Object = kumpulan resources yang mewakili satu fungsi
LwM2M Resource = parameter individual dalam object

Standard Objects (di define IPSO Alliance):
  /0: LwM2M Security      → Server URI, credentials
  /1: LwM2M Server        → Lifetime, binding, notification
  /2: Access Control      → ACL per object
  /3: Device              → Manufacturer, model, firmware version
  /4: Connectivity Monitoring → Network bearer, signal strength
  /5: Firmware Update     → Package URI, update state, result
  /6: Location            → Latitude, longitude, altitude
  /3303: Temperature      → Sensor value, units, range

Example:
  /3303/0/5700  → Temperature sensor 0, resource 5700 (sensor value)
  /3/0/0        → Device object 0, resource 0 (manufacturer)
  /5/0/1        → Firmware Update, resource 1 (package URI)

4.4 Firmware Update (LwM2M OTA)

Step 1: Server write firmware URI ke /5/0/1 (Package URI)
Step 2: Client download firmware (CoAP block-wise transfer)
Step 3: Client update state: /5/0/3 (Update State) → Downloading → Downloaded → Updating
Step 4: Client reboot dengan firmware baru
Step 5: Client register ulang — cek update result /5/0/5

5. LPWAN — LoRaWAN, NB-IoT, LTE-M

5.1 LPWAN Comparison

Teknologi	Frequency	Range	Bandwidth	Battery	Cost Module
LoRaWAN	Sub-GHz (868/915 MHz)	2-15 km	0.3-50 kbps	10+ years	$2-5
NB-IoT	LTE licensed	1-10 km	200 kbps	5+ years	$5-10
LTE-M	LTE licensed	1-10 km	1 Mbps	3+ years	$8-15

5.2 LoRaWAN Architecture

┌──────┐    LoRa RF     ┌──────────┐    IP Backhaul    ┌───────────┐
│ Node │◄──────────────►│ Gateway  │◄─────────────────►│ Network   │
│ (end │                 │ (concentrator) │              │ Server    │
│ device)                └──────────┘                    └───────────┘
                                                            │
                                                      ┌─────┴─────┐
                                                      │ App Server │
                                                      └───────────┘

🔗 Koneksi ke Catatan Lain

Catatan	Koneksi
edge-computing-iot-security-architecture	IoT security architecture
embedded-systems	Sistem embedded untuk IoT
networking-fundamentals-tcpip-bgp	Network layer fundamentals
api-protocols-deepdive	API protocol comparison
wireless-security-deepdive	Wireless communication security
cloud-infrastructure	IoT cloud backend

✅ Checklist

Paham perbedaan MQTT, CoAP, LwM2M
Bisa setup MQTT broker (Mosquitto/EMQX)
Paham QoS levels MQTT dan trade-off masing-masing
Tau kapan pake CON vs NON di CoAP
Paham LwM2M object/resource model untuk device management
Bisa bedain LoRaWAN vs NB-IoT vs LTE-M
Tau protocol serialization yang cocok untuk constrained device
Paham DTLS vs TLS untuk IoT security

Roadmap Belajar

HARI 1: MQTT
  - Setup Mosquitto broker di Docker
  - Publish/subscribe dengan mosquitto_pub/sub
  - Test QoS 0, 1, 2 — lihat perbedaan throughput

HARI 2: CoAP
  - Test CoAP dengan libcoap / coap-client
  - Bandingkan latency CoAP vs HTTP
  - Setup Observe pattern

HARI 3: LwM2M
  - Deploy Leshan (LwM2M server open source)
  - Simulasi device registration + firmware update
  - Test Bootstrap sequence

HARI 4: LPWAN & Mesh
  - Baca spec LoRaWAN 1.1
  - Setup ChirpStack (LoRaWAN network server)
  - Bandingkan Thread vs Zigbee untuk mesh

HARI 5: Security & Production
  - Setup DTLS antara CoAP client dan server
  - Test OSCORE untuk end-to-end encryption
  - Audit security IoT architecture

Bottom Line

IoT protocols bukan cuma soal “pilih yang paling ringan”. MQTT bagus untuk sensor telemetry dengan broker, CoAP lebih cocok untuk device-to-device langsung tanpa infrastruktur, LwM2M essential kalau butuh remote device management. Jangan lupa DTLS untuk CoAP, TLS untuk MQTT — IoT tanpa enkripsi = botnet menunggu waktu.

Lanjutan

Catatan ini fokus ke communication protocols. Untuk security IoT, baca edge-computing-iot-security-architecture. Untuk embedded implementation, baca embedded-systems. Untuk wireless security, baca wireless-security-deepdive.

Azhar's Notes

Navigation

IoT Engineering — MQTT, CoAP, LwM2M & Communication Protocols

📡 IoT Engineering — MQTT, CoAP, LwM2M & Communication Protocols

Daftar Isi

1. IoT Architecture Overview

1.1 Four-Layer Architecture

1.2 IoT Protocol Stack vs Internet Stack

1.3 Protocol Selection Matrix

2. MQTT — Message Queue Telemetry Transport

2.1 MQTT Architecture

2.2 Topic & Wildcard

2.3 QoS Levels

2.4 MQTT 5.0 Improvements

2.5 MQTT Broker Comparison

2.6 Practical MQTT with ESP32

3. CoAP — Constrained Application Protocol

3.1 CoAP vs HTTP

3.2 CoAP Methods vs HTTP

3.3 Confirmable vs Non-Confirmable

3.4 Observe Pattern (CoAP Subscription)

4. LwM2M — Lightweight Machine to Machine

4.1 LwM2M Architecture

4.2 LwM2M Interfaces

4.3 Object/Resource Model

4.4 Firmware Update (LwM2M OTA)

5. LPWAN — LoRaWAN, NB-IoT, LTE-M

5.1 LPWAN Comparison

5.2 LoRaWAN Architecture

🔗 Koneksi ke Catatan Lain

✅ Checklist

Roadmap Belajar

Tampilan Grafik

Daftar Isi