Our digital world is growing rapidly and we have more devices connected to the internet than ever. On top of that each second 80 new devices are added, which introduces new challenges to communication between these devices. MQTT is a lightweight and scalable protocol that shifts the request/response paradigm of the web as it is today to an event-driven publish and subscribe architecture, which is a perfect fit for Internet of Things and M2M use cases. This talk answers the following three questions: Why do we need a paradigm shift, HTTP has been proven to be a good fit for the web? What is MQTT and how does it help to overcome the challenges we have today? How can everybody build their own MQTT application with the implementation that are available for Java developers ? In the last part we will dive into Eclipse Paho and the FuseSource client library and round up the talk with an live demonstration.

1. MQTT with Java
- a protocol for IoT and M2M communication
!
Christian Götz, dc-square

2. IoT?

3. M2M
IoT
IoE
WoT
Web of Things
Internet of Things
Internet of Everything
Machine to Machine
communication
Ubicomp
Ubiquitous computing
CPS
Cyper Physical Systems Pervasive
Computing

4. Technology that connects
Devices
over wired or wireless
communication

5. GPSGPS
GPS
GPS
GPS
GPS
GPS
Detected: Traffic Jam!

6. Hi, I’m Christian Götz
author & speaker
building solutions
CEO &
co-founder
developer
@goetzchr

7. IoT is happening now
WHY?

8. 6,5 per person
DEVICES outnumber
people
0,0
15,0
30,0
45,0
60,0
2003 2010 2015 2020
50,0
25,0
12,5
0,5
6,0
19,5
33,0
46,5
60,0
2003 2010 2015 2020
7,67,36,86,3
250 new every sec
http://blogs.cisco.com/news/cisco-connections-counter/
http://www.cisco.com/web/about/ac79/docs/innov/IoT_IBSG_0411FINAL.pdf
2020
in billions
people
devices

9. Open Hardware is everywhere
Raspberry Pi is a trademark of the
Raspberry Pi Foundation

10. Screenshot from JavaOne 2013
Java back to the roots

11. Screenshot from JavaOne 2013
Java back to the roots

12. HTTP is not suitable
WHY?

13. Request/Response Point-2-Point widely known
HTTP is too verbose

14. Challenges

15. Constrained devices
Bi-directional
Scalability
Unreliable Networks
Push Messaging
Security
… there are more ;)
IoT
HTTP
IoT challenges

16. MQTT is a good fit
WHY?

20. Subscribe

21. Publish

22. Temperaturfühler MQTT-Broker
Laptop
Mobiles Endgerät
publish: “21°C“
publish: “21°C“
publish: “21°C“
subscribe
subscribe

23. munich
schwabing
isarvorstadt
people
temp
people
temp
/ /
MQTT topics 101

24. munich
schwabing
isarvorstadt
people
temp
people
temp
/ /
munich/schwabing/temp
MQTT topics 101

25. munich
schwabing
isarvorstadt
people
temp
people
temp
/ /
munich/+/temp
MQTT topics 101

26. munich
schwabing
isarvorstadt
people
temp
people
temp
/ /
munich/schwabing/#
MQTT topics 101

27. munich
schwabing
isarvorstadt
people
temp
people
temp
/ /
#
MQTT topics 101

28. On top of TCP
Simple
Publish/Subscribe
Architecture
BinaryMinimal Overhead
Designed for unreliable
networks
Data agnostic
MQTT facts

29. - Establishing 1st Connection
(compensated after 5,5 min)
+ Reconnect
+ Maintaining Connection
+ Receiving Messages
+ Sending Messages
less battery better throughput
MQTT (with SSL) vs HTTPS
+ Less Overhead
+ Persistent Sessions
+ Pub/Sub Architecture
Source: http://stephendnicholas.com/archives/1217

30. 1999 2010 2013 2014
Arlen Nipper &
Andy Stanford-Clark
invent MQTT
royalty free OASIS TC
formed
MQTT becomes
Standard
MQTT history

31. Push instead of Poll
Minimal Bandwidth is important Mobile meets Enterprise
Unreliable networks Constrained devices
Low Latency
MQTT use cases

32. MQTT real world usage
https://www.facebook.com/notes/facebook-
engineering/building-facebook-messenger/
10150259350998920

33. Quality of Service
Retained Messages Last Will and Testament
Persistent Sessions Heartbeats
Topic Wildcards
MQTT features

34. MQTT features Quality of Services
QoS 1
QoS 2
QoS 0
B
B
B

35. MQTT features Last Will and Testament
B
Connect
LWT
device123/status: „offline“
B
dropped
device123/status: „offline“

36. MQTT features w/o Retained Messages
B
device1/temp: „23,0“
device1
every 5 min
device2
device1/temp: „23,0“
Delay <= 5min

37. MQTT features Retained Messages
B
device1/temp: „23,0“ R
device1
every 5 min
device2
device1/temp: „23,0“ R
No Delay!

38. MQTT features Persistent Sessions
B
Connect
Subscribe
device/+/status
device/12/status: „1“
1st
B
Re-Connect
device/12/status: „1“
2nd

39. MQTT-SN Overview
Gateway MQTT-Broker
MQTT-SN MQTT / -SN
• UDP instead of TCP
• Topic is just an ID (Preregister/Register)
• Sleeping Clients
• Different types of Gateways
• Discovery Mechanisms
Devices
B

40. MQTT over Websockets

41. MQTT Security
Protocol
Username/Password
Transport
TLS, client certificate authentification
Broker
fine-grained authentication, 3rd party
integration

42. Broker implementations
What ?

43. MQTT Broker Mosquitto
Open Source
Ideal for constraint devices Supports Bridging
Written in C

44. MQTT Broker HiveMQ
High performance broker
Open Plugin System for Java Clustering
Bridging Scalable to > 100.000
connections
Native Websocket support

45. MQTT Broker
+ others
http://mqtt.org/wiki/doku.php/brokers

46. MQTT Broker Public Broker
www.mqttdashboard.com

47. Getting Started
How ?

48. MQTT Implementation

49. Open Source
“Reference Implementation”
Many languages: Java, Javascript,
Lua, C, C++, Go, Python
Active Community
JS Library uses MQTT over
Websockets
Paho facts

50. MqttClient client = new MqttClient(
"tcp://localhost:1883", //URI
"publisher", //Client ID
new MemoryPersistence()); //Persistence
Paho Init Connection

51. MqttClient client = new MqttClient(...);
!
MqttConnectOptions connOptions = new
MqttConnectOptions();
!
connOptions.setKeepAliveInterval(120);
connOptions.setWill("my/status",
"offline".getBytes(), 2, true);
connOptions.setCleanSession(false);
connOptions.setUserName("user");
connOptions.setPassword(„pass".toCharArray(
));
!
client.connect(connOptions);
Paho Init Connection

52. !
!
client.publish("my/topic/123",//topic
"Hello!".getBytes(), //message
1, //QoS
false); //retained
!
!
client.disconnect();
Paho Synchronous API

53. final MqttClient client = new MqttClient(...);
client.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {}
!
@Override
public void messageArrived(String topic,
MqttMessage message)throws Exception
{
System.out.println(new String(message.getPayload()));
}
!
@Override
public void deliveryComplete(IMqttDeliveryToken
token) {}
});
!
client.connect();
client.subscribe("#");
Paho Synchronous API

54. MqttAsyncClient client = new MqttAsyncClient(...);
client.connect(null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken)
{
try {
client.publish(...);
} catch (MqttException e) {}
}
@Override
public void onFailure(IMqttToken asyncActionToken,
Throwable exception) {}
});
!
client.disconnect();
Paho Asynchronous API

55. MQTT Implementation
FuseSource MQTT Client

56. Open Source
3 API Styles
Automatic Reconnect
Maven Central
Less active Community
FuseSource facts

57. MQTT mqtt = new MQTT();
mqtt.setHost("localhost", 1883);
mqtt.setClientId("publisher");
mqtt.setCleanSession(true);
mqtt.setWillTopic("publisher/status");
mqtt.setWillMessage("offline");
mqtt.setKeepAlive((short) 60);
mqtt.setUserName("mqtt-client");
mqtt.setPassword("mqtt");
FuseSource Init Connection

58. BlockingConnection connection =
mqtt.blockingConnection();
!
connection.connect();
!
connection.publish(
"publisher/status", // topic
"online".getBytes(StandardCharsets.UTF_8),
QoS.AT_MOST_ONCE,
false);
FuseSource Blocking API

59. FutureConnection connection =
mqtt.futureConnection();
!
Future<Void> f1 = connection.connect();
f1.await();
!
Future<Void> f2 = connection.publish(
"publisher/status",
"online".getBytes(),
QoS.AT_LEAST_ONCE,
true);
!
f2.await();
!
Future<Void> f3 = connection.disconnect();
f3.await();
FuseSource Future API

60. CallbackConnection connection = mqtt.callbackConnection();
connection.connect(new Callback<Void>() {
public void onSuccess(Void v) {
connection.publish(
"publisher/status",
"online".getBytes(),
QoS.AT_LEAST_ONCE,
false,
new Callback<Void>() {
public void onSuccess(Void v) {}
public void onFailure(Throwable value){}
});
}
!
public void onFailure(Throwable value) {}
});
FuseSource Callback API

61. It’s Showtime
Demo

62. Demo from device to the web with MQTT
https://github.com/dc-square/mqtt-with-paho-eclipsecon2013
available on

63. Demo Under the hood

64. Danke!
Thanks!
@goetzchr