MQTT mag "das" Thema für das IoT (Internet der Dinge) sein, es ist dennoch auch für das Monitoring von Maschinen und Dienste sehr interessant. Wir besprechen was das MQTT Protokoll ist, wozu es eingesetzt werden kann, und zeigen Anwendungen für MQTT. Selbstredend werden wir auch über das eine oder andere Gadget welches MQTT "spricht" reden.

1. MQTT
it’s also for Monitoring
Jan-Piet Mens
November 2015
@jpmens

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

3. transport protocol
binary payload, 256MB, (+2 bytes),
fast,
lightweight, ideal for low-
bandwith, high-latency networks

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

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

6. more features
keepalive
last will & testament,
decoupled senders/recipients,
durable messages

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
http://mosquitto.org

11. VerneMQ
Erlang, plugins, clustering, modules
http://verne.mq

12. HiveMQ
Java, plugins, Websockets, clustering, modules
http://hivemq.com

13. MQTT brokers
$SYS topic
$SYS/broker/clients/total 1771
$SYS/broker/messages/received 36597465
$SYS/broker/messages/sent 39714120
$SYS/broker/messages/stored 2941
$SYS/broker/bytes/received 2830787008
$SYS/broker/bytes/sent 3810653433
$SYS/broker/version mosquitto version 1.4
$SYS/broker/publish/messages/received 19798673
$SYS/broker/publish/messages/sent 30622855
$SYS/broker/publish/bytes/received 1868229299
$SYS/broker/publish/bytes/sent 3185942282

14. bridging

15. CLI utilities
mosquitto_sub -v
[-h localhost] [-p 1883]
[--cafile file]
[--cert file --key file]
[-u username [-P password]]
[ --tls-version tlsv1.2 ]
-t 'topic/#'
subscribe
publish
mosquitto_pub
...
[-r]
-t topic
-m payload

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

17. 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

18. 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 %s" % (msg.topic, str(msg.payload), userdata)
data = { 'type' : 'conference' }
mqttc = paho.Client(userdata=data)
mqttc.on_connect = on_connect
mqttc.on_message = on_message
mqttc.connect("localhost", 1883, 60)
mqttc.loop_forever()

19. Python API: SUB
$ mosquitto_pub -t 'conf/thirsty' -m 'Beertime?'
$ mosquitto_pub -t 'conf/catering' -m 'Coffee is ready'
$ ./sub.py
conf/thirsty Beertime? {'type': 'conference'}
conf/catering Coffee is ready {'type': 'conference'}

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

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

22. temperature: Arduino
huh?

23. all good!

24. via MQTT to mobile

25. collectd MQTT
collectd/localhost/memory/memory-free 1447687344.367:8562388992
collectd/localhost/interface-lo0/if_packets 1447687344.367:24.4002854838096:..
collectd/localhost/interface-lo0/if_errors 1447687344.367:0:0
collectd/localhost/interface-gif0/if_octets 1447687344.367:0:0
LoadPlugin mqtt
<Plugin mqtt>
<Publish "name">
Host "localhost"
Port 1883
ClientId "collectd-tiggr-pub"
QoS 0
Prefix "collectd"
StoreRates true
Retain false
</Publish>
<Subscribe>
...
</Subscribe>
</Plugin>

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

27. mqtt.org
@mqttorg