Powering your next IoT application with MQTT - JavaOne 2014 tutorial
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When it comes to connecting physical objects from daily life to the internet, you’re faced with several challenges. MQTT is a protocol for the Internet of Things that addresses the aforementioned challenges and makes it possible to build scalable sensor networks. This tutorial aims to give you a hands-on experience with the MQTT protocol and walk you through the creation of an end-to-end M2M/Internet of Things application, using open source Java components such as Eclipse Paho, Mosquitto, and Kura. You will leave the session knowing all the cool features of MQTT and how you can integrate it into your Java solutions.
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Powering your next IoT application with MQTT - JavaOne 2014 tutorial
- 1. Powering your next IoT application with MQTT Julien Vermillard Benjamin Cabé
- 2. Your devoted presenters :-) Julien Vermillard / @vrmvrm ● Software Engineer at Sierra Wireless ● Implementing various protocols for our cloud service (AirVantage) ● Apache Software Foundation member ● Eclipse committer on Californium, Wakaama and Leshan
- 3. Your devoted presenters :-) Benjamin Cabé / @kartben ● IoT Evangelist at the Eclipse Foundation ● Hack things – Arduino, Raspberry Pi, Glass, … ● Traveler and photographer
- 4. Agenda Internet of Things 101 What protocol should I use? MQTT What is MQTT? Features overview MQTT at Eclipse HANDS-ON! More MQTT cool stuff
- 5. Tutorial goal Go from our first dead simple MQTT client app to a complete end-to-end solution for … reporting, consolidating and charting sensor data … coming from a connected greenhouse
- 6. Tutorial steps Step 0 The greenhouse setup Step 1 Write your first MQTT client Step 2 Create an MQTT bot to consolidate live data Step 3 Live JavaFX dashboard Photo by Clover_1
- 7. What you will need Eclipse IDE Basic Java knowledge Your brainzzz
- 9. Machine-to-Machine? Internet of Things?
- 10. Technology that supports wired or wireless communication between devices ❝
- 11. IoT protocols … devices are constrained … network is constrained … applications are heterogeneous
- 12. Different needs Device Management Radio statististics, device configuration, … OMA-DM, TR-069, Lightweight M2M… Local sensor networks Transmit sensor data, usually over RF or PLC Zigbee, X10, Bluetooth Smart, … End-user applications Display sensor data on mobile app, dashboards, … HTTP, Websockets, ...
- 13. Find your way through the IoT protocols jungle Continental 1/2/3, Thursday @11.00am
- 15. MQTT?
- 16. MQTT? M is for Messaging… (mmmmaybe!) Q is not for Queue Publish/Subscribe protocol Lightweight (bandwidth, battery, …)
- 17. PUB ǶeǹǹǷe232/ǹemp SUB ǶeǹǹǷe232/ȃ ǶeǹǹǷe232/ǹemp 21.3 21.3
- 18. MQTT history … it’s not new! Invented in 1999 (Andy Stanford-Clark, Arlen Nipper) Royalty-free since 2010 Being standardized at OASIS - final spec to be released soon
- 19. Neat MQTT features Wildcards Quality of Service Last Will & Testament Retained Messages
- 20. MQTT Features | Wildcards ● The number sign (#) is a wildcard character that matches any number of levels within a topic. ● The plus sign (+) is a wildcard character that matches only one topic level Examples mygreenhouse/sensors/# +/sensors/temperature
- 21. MQTT Features | QoS QoS flag allows to control the level of assurance for delivery you want when publishing a message to the broker
- 22. MQTT Features | QoS 0 QoS flag allows to control the level of assurance for delivery you want when publishing a message to the broker A message published with QoS=0 will be received at most once (“fire & forget”) by subscribed clients
- 23. MQTT Features | QoS 1 QoS flag allows to control the level of assurance for delivery you want when publishing a message to the broker A message published with QoS=1 will be received at least once (acknowledged delivery) by subscribed clients
- 24. MQTT Features | QoS 2 QoS flag allows to control the level of assurance for delivery you want when publishing a message to the broker A message published with QoS=2 will be received exactly once (assured delivery) by subscribed clients
- 25. MQTT Features | Last Will & Testament IoT devices can come & go on the network quite often and in a very unpredictable way Last Will & Testament allows to notify interested parties to an abnormal disconnection of a client The Last Will & Testament (if any) is part of the initial connection message
- 26. MQTT Features | Retained messages The Retained flag allows a published message to be stored on the broker, so as possible receivers can subscribe later and still receive the message
- 27. MQTT at Eclipse Moquette
- 28. Eclipse Paho Open-source implementations of MQTT clients Pick your language! Java, JavaScript, C/C++, Go, Obj C, Lua, Python … http://eclipse.org/paho https://dev.eclipse.org/mailman/listinfo/paho-dev
- 29. Eclipse Mosquitto Lightweight server implementation of MQTT (MQTT-SN to come), written in C Lightweight? Executable is ~120kB ~3MB RAM with 1000 clients connected http://eclipse.org/mosquitto https://dev.eclipse.org/mailman/listinfo/mosquitto-dev
- 30. Eclipse Moquette A pure Java broker Supports QoS 0, 1, 2 Websockets Event-driven: based on Netty and LMAX disruptor
- 31. Hands-on!
- 32. Step #0 iot.eclipse.org MQTT broker YOU :-)
- 33. Step #0 The Kura application can be seen as an MQTT client that: ● publishes sensor data to topics ● is subscribed to commands Root topic: javaonedemo/eclipse-greenhouse/ Sensor data on sensors/... subtopic, Actuators on actuators/... subtopic
- 34. Creating a Java Internet of Things Gateway Continental 1/2/3, Tuesday @2.30pm
- 35. End-to-End IoT Solutions with Java and Eclipse IoT Continental 1/2/3, Today @11.00pm
- 36. Contents of the USB stick ● Eclipse IDE for Windows, Linux and OS X ● Sample projects to be imported in your workspace + Paho java client JAR file ● Completed projects
- 37. Tutorial source code Check out: https://github.com/kartben/mqtt-tutorial-javaone2014
- 38. Getting started ● Launch Eclipse ● Import projects contained on the USB stick ○ File > Import… > Existing projects into workspace
- 39. Step #1 Use the Java MQTT client from Paho to exchange our first messages with a broker Key concepts: ● Connect/disconnect to a broker ● Topic structuring best practices ● Publish/subscribe messages ● QoS
- 41. MQTT Topics best practices Photo Credit:oskay
- 42. MQTT Topics best practices That’s a tough question… are there best practices as to how to organize your local filesystem…? Photo Credit:oskay
- 43. MQTT Topics best practices Photo Credit:oskay ● Topic hierarchy is what will allow you to do smart wildcard matching ○ objectID/temp is better than temp/objectID ● No need to start with a ‘/’ ● Persist your topics if you can afford it Interesting thoughts in this session from IoT Day Grenoble https://www.youtube. com/watch?v=yQAsjGFewk8
- 44. MQTT for Java API MqttClient ● Main class allowing to connect to a broker MqttMessage ● What you send to or receive from a broker ● Arbitrary binary payload (ie byte array) MqttCallback ● For a given MqttClient, the MqttCallback is where you handle received messages, delivery ACK, and loss of connection
- 45. Connecting to a broker MqttClient#connect(serverURI, clientId) URI can be something like: ● tcp://iot.eclipse.org:1883 ● ssl://my.secured.broker:8883 The client ID must be unique on a given broker Its main use is keeping subscriptions intact for unreliable endpoints (see the Clean session flag)
- 46. Retrieving data Complete step1 project: 1. Connect to iot.eclipse.org 2. Subscribe to: javaonedemo/eclipse-greenhouse/sensors/# 3. Observe the data coming in 4. (optional) Publish a message (‘on’ or ‘oDzDz’) to: javaonedemo/eclipse-greenhouse/actuators/light - Think about what QoS is best suited for controlling the LED - To persist or not to persist?
- 47. Questions?
- 48. Step #2 Leverage retained messages to build a bot that consolidates (min, max, avg) sensor data Key concepts: ● Asynchronous client ● Retained messages ● Data consolidation
- 50. Data consolidation workflow “PUBLISH” javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.2
- 51. Data consolidation workflow “PUBLISH” javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.2 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.2 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.1 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.26 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.0 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.9
- 52. Data consolidation workflow javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.2 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.1 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.26 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.0 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.9 “PUBLISH” greenhouse/LIVE/benjamin-bbb/data/temperature Payload: 23.2 Local consolidation
- 53. Data consolidation workflow javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.2 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.1 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.26 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.0 javaonedemo/eclipse-greenhouse/sensors/temperature Payload: 23.9 “PUBLISH RETAIN” javaonedemo/CONSOLIDATED/… eclipse-greenhouse/sensors/… 2014/09/28/09/43 Payload: 23.312 “PUBLISH” greenhouse/LIVE/benjamin-bbb/data/temperature Payload: 23.2 Local consolidation
- 54. MqttAsyncClient Same as MqttClient but allowing to perform operations asynchronously! ● i.e. it will allow us to asynchronously publish a message from within the messageArrived callback ● Methods are not very different from MqttClient except that they optionally accept an IMQTTActionListenerCallback (called when operation has finished), and return an IMqttToken to be used for tracking the completion of a task
- 55. Questions?
- 56. Step #3 Use JavaFX Charts to display live sensor data
- 57. JavaFX Charts
- 58. Questions?
- 59. Other cool MQTT uses MQTT over WebSockets ● Build a web UI with no backend ● Broker support in Mosquitto, Moquette, … ● Many JS-based time-series graph engines: D3.js, Rickshaw, … https://www.eclipse.org/paho/clients/js/
- 60. Other cool MQTT uses MQTT on embedded devices ● Arduino, ● mbed, ● etc. https://www.eclipse.org/paho/clients/c/embedded More info on Ian Cragg’s blog.
- 61. Other cool MQTT uses MQTT on Google Glass ● You just need a regular Java Paho client! ● “OK Glass, control the roof!” ● You might want to check out the Android service available in Paho’s Java ‘develop’ branch
- 62. Thanks! More questions? Feel free to contact us! Benjamin Cabé @kartben benjamin.cabe@eclipse.org Julien Vermillard @vrmvrm jvermillard@sierrawireless.com