MQTT for sysadmins and for fun Jan-Piet Mens April 2014 @jpmens 

@jpmens: consultant, author, architect, part-time admin, small-scale fiddler, loves LDAP, DNS, plain text, and things that work. 

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

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

security TLS authentication ACLs TLS-PSK (payload encryption) 

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

more features keepalive last will & testament 

compare HTTP ? request/response, verbose, push, poll, nobody hears clients die 

PUB/SUB decoupled senders recipients: flexibility one producer to many (changing) consumers no queueing broker can hold messages until subscriber reconnects durable (retain) Last Will and Testament single TCP port (easy on firewalls) 

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

PUB/SUB cauldron 

MQTT brokers the server bit of MQTT 

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

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

more brokers RSMB, Mosca, Apollo, RabbitMQ 

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 1.2 $SYS/broker/publish/messages/received 19798673 $SYS/broker/publish/messages/sent 30622855 $SYS/broker/publish/bytes/received 1868229299 $SYS/broker/publish/bytes/sent 3185942282 

bridging 

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] -m payload 

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

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 payload topic 

Python API: SUB #!/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() mqttc.on_connect = on_connect mqttc.on_message = on_message mqttc.connect("localhost", 1883, 60) mqttc.loop_forever() callbacks 

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 

devices 

devices 

practical solutions alerting, metering, logging, location awareness, tracking, automation, and controlling 

MQTT out there Github (notifications), power metering, trains, FaceBook messenger, connected cars, temperature monitoring, host monitoring (load) 

system utilities Ansible (notifications), Fluentd (logging), Diamond (system metrics), mqtt-watchdir, Jenkins, (build logs), 

database persistence SUB and store in any SQL or NoSQL database 

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

job control, reporting https://gist.github.com/jpmens/7101170 $ mosquitto_sub -v -t 'processes/#' processes/run.sh Starting processes/run.sh Still running processes/monitor/spec1 Starting processes/run.sh Still going strong at Tue Oct 22 15:49:07 CEST 2013 processes/run.sh That's it, folks! 

WebSockets HiveMQ, WSS, lighttpd mod_websocket 

WebSockets http://www.hivemq.com/demos/websocket-client/ 

No content

No content

Node-RED http://nodered.org 

mqtt.org @mqttorg