Walter  Coli+  -­‐  Kris  Steenhaut  -­‐  Niccolo’  de  Caro  

Integra9ng  Wireless  Sensor  Networks  with  the  Web  

Vrije  Universiteit  Brussel  –  ETRO  Department.    

Introduc9on  

Internet  of  Things    Trillions  of  smart  objects  connected  to  the  Internet  

New  scenario  for  Smart  Metering,  E-­‐health,  Logis9cs,  …    

IP  for  smart  objects    IP  for  Smart  Objects  alliance  (IPSO)    IETF  6LoWPAN  and  RPL    

Introduc9on  

Web  of  Things    REST  architecture  (URI/JSON/XML/…)  Resource  manipula9on  with  HTTP  (GET,  PUT,  POST,  …)  

IETF  CoAP    HTTP  func9onali9es  re-­‐designed  for  constrained  devices  Extra  func9onali9es  added  

Contribu9ons  

CoAP  vs  HTTP  Benefits  of  CoAP  for  power  consump9on  

Web/WSN  integra>on  RESTful  WSN  accessed  from  Web  Browser    

CoAP  

Transport  Protocol  UDP,  low  overhead  and  mul9cast  support  

Dual  layer  Transac9on  layer  for  message  exchange    

HTTP

TCPIP

Request/ResponseTransaction

UDP6LoWPAN

CoAP

Request/Response  layer  for  resource  manipula9on  

CoAP  

Small  message  overhead  Fixed-­‐length  compact  binary  header  of  4  bytes  

Observa>ons  Observa9on  rela9onship  between  client  and  resource  

Con9kiMAC  uIPv6/SICSLoWPAN  CoAP/HTTP  Server  

TmoteSky  CoAP/HTTP  Client  

[ubuntu]  

CON  GET  coap://[mote_ip_address]:61616/readings  

ACK  CONTENT  2.05  {“sensor”:”212:7400:2:202”,”readings”:{“hum”:45,”temp”:24.5}}  

[polling  frequency  =  10’’]  

CoAP/HTTP  testbed  

Traffic  [  bytes  transferred  per  transac9on  ]  

CoAP  

HTTP  

154

1451

CoAP/HTTP  comparison  

Power  consump>on  [  mW  ]  

CoAP  

HTTP  

0.744

1.333 (Evalua9on  based  on  Energest  output)  

CoAP/HTTP  comparison  

BaMery lifetime [  days  ]  

CoAP  

HTTP  

151

84

CoAP/HTTP  comparison  

Study  case:  Greenhouse  monitoring  

The  end-­‐to-­‐end  system  

USER  

HTTP  

Web  App  Server  

CoAP    client  

Apache  CouchDB  

Linux  Ubuntu  

WSN  

CoAP  

GATEWAY  =  Ubuntu  machine              +  Con9ki  router  (USB)  

3  BUILDING  BLOCKS:  

The  Gateway  

 the  Non-­‐SQL  database  CouchDB  (JSON  storage  format)  -­‐  contains  WSN  data  

 the  CoAP-­‐client  communicates  with  the  WSN  and  stores  data  into  the  database,  or  passes  them  to  the  Web  app  server  

 the  Web  App  server  

-­‐  from  the  CoAP-­‐client  for  real-­‐>me  polls  -­‐  from  the  DB  for  historical  data  and  stats  

Includes  a  set  of  services  used  to  retrieve  data:  

WSN  features:  

The  Wireless  Sensor  Network  

l   based  on  Con9ki  OS  l   mesh  topology  network  l   Tmote  Sky  motes  l   RPL:  mul9-­‐hop,  re-­‐rou9ng  in  case  of  node  failure  l   Stack:  CoAP/UDP/IPv6/6LowPAN/802.15.4  

gateway  browser  HTTP/AJAX  

The  Web  Applica9on  

Temperature:  24.5°C  Humidity:  35%  

@15:34  April  12,  2011  

February  ‘10  Hello!  

""

""

Thanks  for  your  auen9on