This document discusses the use of MQTT, a messaging protocol designed for unreliable networks, for monitoring various devices. It outlines the technical aspects, including security features and programming examples using the ESP8266 microcontroller, along with potential applications in home automation and device monitoring. Additionally, it mentions various tools and platforms that integrate with MQTT for alerting and logging purposes.

1. Small Things
for Monitoring
Jan-Piet Mens
November 2016
@jpmens

2. @jpmens: consultant, part-
time admin, small-scale
fiddler, loves DNS,
plain text, and things
that work. Dreamed up
OwnTracks & wrote jo

3. Today’s special
MQTT
ESP8266
for monitoring stuff

4. MQTT is a standard,
a transport,
PUB/SUB messaging,
designed for
unreliable networks
MQTT

5. security
TLS
authentication
ACLs
TLS-PSK
(payload encryption)

6. Quality of Service
0 At most once
1 Assured delivery
2 Once only

7. topic names
UTF-8, hierarchical, wildcards
temperature/room/living
devices/#
finance/+/eur/rate

8. PUB/SUB cauldron

9. MQTT brokers
the server bit of MQTT

10. Mosquitto
C, fast, lightweight, ACLs (plugin),TLS,TLS-PSK, bridge,
Websockets, logging via $SYS, FLOSS
http://mosquitto.org

11. bridging

12. CLI utilities
mosquitto_sub -v
[-h localhost] [-p 1883]
[--cafile file]
[--cert file --key file]
[-u username [-P password]]
-t 'topic/#'
subscribe
publish
mosquitto_pub
...
[-r]
-t topic
-m payload

13. languages
Lua, Python, C, JavaScript, Perl, Ruby, Java, ...

14. Python API: PUB
#!/usr/bin/env python
import paho.mqtt.publish as mqtt
mqtt.single('conf/hello', 'Hello MQTT')
$ mosquitto_sub -h localhost -v -t 'conf/#'
conf/hello Hello MQTT
payloadtopic

15. Python API: SUB
callbacks
#!/usr/bin/env python
import paho.mqtt.client as paho
def on_connect(mosq, userdata, rc):
mqttc.subscribe("conf/+", 0)
def on_message(mosq, userdata, msg):
print "%s %s" % (msg.topic, str(msg.payload))
mqttc = paho.Client(userdata=None)
mqttc.on_connect = on_connect
mqttc.on_message = on_message
mqttc.connect("localhost", 1883, 60)
mqttc.loop_forever()

16. Python API: SUB
$ mosquitto_pub -t 'conf/thirsty' -m 'Beertime?'
$ mosquitto_pub -t 'conf/catering' -m 'Coffee is ready'
$ ./sub.py
conf/thirsty Beertime?
conf/catering Coffee is ready

17. The hardware …
EUR 22.83
Flash/RAM 16 / 64
USB 2
LAN/WAN 1 / 1
WiFi 802.11 b/g/n
GL-Inet AR150

18. Small, but too much
EUR 50 - 100

19. ESP8266
Low-cost micro controller
full TCP/IP stack
A bit like an Arduino (same IDE, or Lua)
but with on-board WiFi (!)
and really inexpensive
Different form factors

20. ESP8266
EUR 1.50
ESP-01
EUR 2.60NodeMCU
EUR 1.50
ESP-12

21. Electrodragon
EUR 5.50
http://www.electrodragon.com

22. Sonoff
EUR 4.47
https://www.itead.cc/sonoff-wifi-wireless-switch.html

23. Wemos D1 mini
EUR 4.00
Flash/RAM 4MB / 64 KB
Voltage 3.3V
Digital I/O 11
Analog 1

24. Wemos shields
EUR 1.95
EUR 4.50
EUR 1.40
EUR 2.90

25. Homie-ESP8266
#include <Homie.h>
HomieNode buttonNode("button", "button");
void loopHandler() {
int buttonValue = debouncer.read();
/* ... */
if (Homie.setNodeProperty(buttonNode, "open",
buttonValue ? "true" : "false", true)) {
}
}
void setup() {
debouncer.attach(PIN_BUTTON);
Homie.setFirmware("button-homie", "1.0.0");
Homie.registerNode(buttonNode);
Homie.setLoopFunction(loopHandler);
Homie.setup();
}
void loop() {
Homie.loop();
debouncer.update();
}
https://github.com/marvinroger/homie-esp8266

26. Arduino IDE

27. Le bouton
devices/cea191e0/$nodes button:button
devices/cea191e0/$online true
devices/cea191e0/$name Le bouton
devices/cea191e0/$localip 192.168.8.151
devices/cea191e0/$fwname button-homie
devices/cea191e0/$fwversion 1.0.0
devices/cea191e0/$signal 100
devices/cea191e0/button/open true

28. homie-ota
https://github.com/jpmens/homie-ota
Retro/Vintage-style

29. Monitoring
Temperature, movement (PIR), humidity, inexpensive sensors,
many examples, LWT, mqttwarn for integration, Node-Red

30. alerting: mqttwarn
https://github.com/jpmens/mqttwarn

31. practical solutions
alerting, metering, logging, location awareness, tracking,
automation, and controlling, host monitoring

32. MQTT in the wild
Graylog, beaver, Ansible, RabbitMQ, collectd, openHAB, Github,
Wireshark, Flukso, RemakeElectric, Jenkins, Diamond, OwnTracks

33. mqtt.org
@mqttorg

34. Particle Photon
EUR 19.00

35. Particle Electron
EUR 70.00