Analysts predict that in 2020 50 billion devices are connected to the internet. Together with the fact that more and more of these "things" are connected over the cellular network, new challenges are introduced to the communication of Internet of Things (IoT) and machine-to-machine (M2M) scenarios. There are a lot of protocols which claim to be ideal for these use cases, for example MQTT and COAP. In this talk you will get an overview of commonly used protocols and their underlying architectural styles. We will also look at advantages/disadvantages, use cases and the eco-system around them for Java developers.

1. Christian Götz | dc-square GmbH
How do Things talk?
IoT Application Protocols 101

2. Talking leads to Knowledge

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

4. ...but wait
who’s talking here

5. author & speaker
things
speech therapist ;)
CEO &
co-founder
developer
@goetzchr

6. THINGS talk?

7. THINGS?

8. Consumer Goods

9. Industry Machines

10. objects in our everyday life

11. logistics has a lot of things...

12. 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

13. Technology that connects
Devices
over wired or wireless
communication

14. why should I care ?

15. Source: http://www.cisco.com/web/about/ac79/docs/innov/IoT_IBSG_0411FINAL.pdf
0
12,5
25
37,5
50
2003 2010 2015 2020
3,4
1,8
0,08
World Population Connected Devices
Ratio
6,5

16. new devices per second
http://blogs.cisco.com/news/cisco-connections-counter/
2013 2014 2020
250
100
80

17. finally a use case for IPv6 ;)

18. Open Hardware
simple
accessible
affordable
Raspberry Pi is a trademark of the Raspberry Pi Foundation

19. Developers
are the new King Makers
… if you don’t believe me, read this book ;)
http://thenewkingmakers.com/

20. So how do these
things talk?

22. HTTP/REST
used since 1991
widely known and adapted
request/response
point 2 point
HTTP 2.0 - still work in progress

23. Challenges
Constrained devices
Bi-directional communication
Scaling to 100.000s of devices
Unreliable networks
Push messaging
Security
HTTP
IoT

24. CoAP
Constrained Application Protocol
CoAP HTTP
Introducing . . .

25. CoAP Message
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver| T | TKL | Code | Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token (if any, TKL bytes) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options (if any) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 1 1 1 1 1 1 1| Payload (if any) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

26. protocol stack
CoAP
UDP
6LoWPan
HTTP
TCP
IP
vs

27. Message Flow
Client Server
Request
Response
Non-Confirmable Message
1/2

28. Message Flow
Client Server
Request
Response
Ack
Ack
Confirmable Message
2/2

29. URL REST style
coap://host:port/path?param=value
coap://localhost:5683/temp
coap://server/temp/critical?above=42

30. Observe
Server
Client
http://tools.ietf.org/html/draft-ietf-core-observe-13
GetOptObserve
Response
Response
Response
Response
10 ℃ 8 ℃ 7 ℃ 5 ℃ 4 ℃
10 ℃ 8 ℃ 7 ℃ 4 ℃
lost
Response
5 ℃

31. Discovery of Resources
/.well-known/core
Multicast
Content-Negotiation
Proxy CoAP-HTTP and HTTP-CoAP
DTLS
Other features

32. Tools
Californium and Copper Logo from http://people.inf.ethz.ch/mkovatsc/
Californium & Copper
+
More Implementations
http://en.wikipedia.org/wiki/Constrained_Application_Protocol#Implementations

34. XMPP at a glance
• developed for chat
• based on XML
• extensible
• decentral / inter-server
• TLS and SASL

35. Typical XMPP Flow
<iq type =’get’
from =’client@jax.de’
to =‘tempsensor@jax.de’
id =’S0001’>
<req xmlns =’urn:xmpp:iot:sensordata’
seqnr =’1’ momentary =’true’ >
</iq>
1/3

36. <iq type =’result’
from =’client@jax.de’
to =‘tempsensor@jax.de’
id =’S0001’>
<accepted xmlns =’urn:xmpp:iot:sensordata’
seqnr =’1’/ >
</iq>
2/3

37. <message from =’...’ to =’...’>
<fields xmlns=’urn:xmpp:iot:sensordata’ seqnr =’1’
done =’true’>
<node nodeId =’Device01’>
<timestamp value=‘2013-03-07T16:24:30’>
<numeric name =’Temperature’
momentary =‘true’ automaticReadout =’true’
value =’23.4’ unit =’°C’ >
</timestamp>
</node>
</fields>
</message>
3/3

38. From chat to IoT - status quo

39. Who’s a friend ?

40. Source: Wikipedia
implementations

41. XMPP IoT Extensions
323 Sensor Data experimental 04/2014
324 Provisioning experimental 03/2014
325 Control experimental 04/2014
326 Concentrators experimental 03/2014
347 Discovery experimental 04/2014
??? Interoperability not approved
??? Pub/Sub IoT not existent
Source: http://xmpp.org/xmpp-protocols/xmpp-extensions/

42. More XEPs
EXI (Efficient XML Interchange)
Service Discovery
<query xmlns =’http://jabber.org/protocol/disco#info’/ >

43. it’s still XML

44. Tools
Clients
http://xmpp.org/xmpp-software/libraries/
Server
http://xmpp.org/xmpp-software/servers/

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

47. Topics
rheingoldhalle
Goldsaal A
Goldsaal B
people
temp
people
temp
/ /
1/5

48. rheingoldhalle
Goldsaal A
Goldsaal B
people
temp
people
temp
/ /
rheingoldhalle/Goldsaal-A/temperature
2/5

49. rheingoldhalle
Goldsaal A
Goldsaal B
people
temp
people
temp
/ /
rheingoldhalle/+/temp
3/5

50. rheingoldhalle
Goldsaal A
Goldsaal B
people
temp
people
temp
/ /
rheingoldhalle/Goldsaal B/#
4/5

51. rheingoldhalle
Goldsaal A
Goldsaal B
people
temp
people
temp
/ /
#
5/5

52. Characteristics
• Topics
• lightweight
• QoS Levels
• Retained / LWT
• MQTT over Websockets
• Bridging
• SSL

53. Broker
• central communication point
• different implementations
• additional features
+ others
http://mqtt.org/wiki/doku.php/brokers

54. MQTT-SensorNetworks
MQTT for WSN
utilizes UDP
Gateway to MQTT
Topic Preregistration
Sleeping Clients
-SN

55. protocol stack
MQTT-SN
UDP
6LoWPan
MQTT
TCP
IP

56. Tools
Public Broker
http://mqttdashboard.com
Java-Broker
with Plugin SDK
Client Lib

58. CONNECT
accept-version:1.0,1.1,2.0
host:example.com/stomp
login:guest
passcode:guest
^@
Simple/Streaming Text Oriented Messaging Protocol

59. SEND
destination:/queue/test
This is a simple STOMP Message!
^@
Simple/Streaming Text Oriented Messaging Protocol

60. Facts
• simple
• text-based
• publish/subscribe
• Websockets support
• Transaction support

61. Tools
reference broker impl
Stampy
server/client impl
+ others
http://stomp.github.io/implementations.html

62. CoAP
HTTP

63. protocol war

64. You Mean the One
and Unique Solutions
For All Problems
DOES NOT
EXIST?

65. coexistence

66. How to choose a protocol
• How constrained are the devices?
• Reliable/unreliable network?
• What is the message rate?
• How is the data processed further?
• Push or Pull ?

68. @goetzchr
Thanks