Tuesday, 03 Apr 2012

CoAP, Copper, and Embedded Web Resources

Matthias Kovatsch kovatsch@inf.ethz.ch

Internet of Things Zurich Meetup, Zurich, Switzerland

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

What About Really Cheap Platforms?

2

Smart

Dust

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

Outcome

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Wireless Sensor Networks

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

IP Connectivity through 6LoWPAN

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IP router

Web server

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

Constrained Application Protocol (CoAP)

A new Web-like protocol based on REST

5

URIs

Internet Media Types

Extensible option headers

GET, PUT, POST, DELETE

Interoperability

Common

programming model

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

The CoAP Universe

IETF working group «Constrained RESTful Environments» RESTful Web services for mote-class devices

Transparent mapping to HTTP

Observing Resources publish/subscribe

Group communication IP multicast

CoRE Link Format Web linking RFC, discovery

Caching proxies RESTful caching

Resource directories sleepy nodes

Blockwise transfers bulky data

…

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CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

CoAP is Optimized, Binary…

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CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

Copper (Cu) CoAP user-agent

8

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

Embedded Web Resources

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/consumption

/consumption/consumed

/consumption/generated

/max/power

/max/current

/max/voltage

/meter/power

/meter/current

/meter/voltage

/meter/frequency

/meter/phase

/meter/reactive

/reset

/switch

/debug/…

/config/date

/config/mode

/config/time

/debug/…

/sensors/battery

/sensors/temp

/sensors/user

/set/valve

/set/target

/actuators/leds

/debug/channel

/debug/neighbors

/debug/observers

/debug/routes

/sensors/batter

y /sensors/button

/sensors/humidity

/sensors/light

/sensors/temperature

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

Profiles for Embedded Web Resources

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IPSO Profile

Pure RESTful design

Treats CoAP and HTTP equally

Currently still cryptic identifiers

due to size optimizations

(e.g., /lt for light)

Smart Energy Profile 2.0

SOAP-like service design

over REST

Currently only defined for

HTTP, CoAP in the draft

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

CoAP Open Source Implementations*

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Erbium for Contiki

REST Engine

For embedded devices

Enables thin server

architecture

Copper for Firefox

CoAP user-agent

For user interaction

Integration and testing

tool

Californium in Java

CoAP framework

For the back-end

Clients, servers,

and proxies

Available on GitHub: https://github.com/mkovatsc

Successfully tested at the ETSI IoT CoAP Plugtests, Paris, France, Mar 2012: http://www.etsi.org/plugtests/coap/coap.htm *

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

THANK YOU

Questions?

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CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

Protocol Stack

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Layer Protocol

Application CoAP

Transport UDP

Network IPv6 / RPL

Adaption 6LoWPAN

MAC CSMA / link-layer bursts

Radio Duty Cycling IEEE 802.15.4e / ContikiMAC

Physical IEEE 802.15.4

CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

CoAP Message Format

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 | OC | Code | Message ID |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Options (if any) ... | (Terminator) |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Payload (if any) ...

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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CoAP, Copper, and Embedded Web Resources Matthias Kovatsch – ETH Zürich

CoAP Option Encoding

0 1 2 3 4 5 6 7

+---+---+---+---+---+---+---+---+

| Option Delta | Length | for 0..14

+---+---+---+---+---+---+---+---+

| Option Value ...

+---+---+---+---+---+---+---+---+

for 15..270

+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

| Option Delta | 1 1 1 1 | Length - 15 |

+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

| Option Value ...

+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

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