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REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
REST APIs for an Internet of Things
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REST APIs for an Internet of Things

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  • 1. REST  APIs     for  the     Internet  Of  Things   Michael  J  Koster   Open  Source  Internet  Of  Things   Meetup  19  March  2014  
  • 2. Resource  oriented  API   •  Resource  ==  web  resource  (URI)   •  Resources  change  state  in  response  to  what  is   being  sensed   •  Actuator  changes  state  in  response  to  web   resource  update   •  Abstract  data  sources  and  sinks   •  REST  API  has  2  important  characterisJcs  for   IoT  use  case…  
  • 3. RepresentaJonal  State  Transfer   •  Resource  interacJon  through  exchange  of   representaJon  of  resource  state   •  E.g.  a  representaJon  of  the  state  of  a   temperature  sensor  might  be  “63.6”     •  Convenient  for  applicaJon  soTware  to  use   read/write  semanJcs  to  interact  with   resources   •  Stateful  resource  representaJons  =>  Stateless   applicaJon  soTware  
  • 4. Based  on  Hypermedia   •  Use  of  web  links  to  locate  resources  of   interest   •  IoT  needs  machine-­‐readable  links  that  enable   applicaJon  soTware  to  discover  things  of   interest   •  Subset  of  web  linking,  semanJc  web  using   relaJon/aribute   •  Links  encode  metadata  about  the  resource,   e.g.  type=‘temperature’,  ct=‘applicaJon/json’  
  • 5. Web  Linking  for  IoT   •  Links  are  managed  in  2  ways   •  Object  encapsulaJon:  self-­‐describing  objects   have  links  associated  with  endpoint,  e.g.  ./ well-­‐known/core   •  Resource  Directory:  Directories  and  Catalogs   of  links,  stored  at  well-­‐known  locaJons,  that   point  to  resources  and  to  other  catalogs  
  • 6. Web  Linking  for  IoT   •  Links  can  be  registered  with  a  Resource  Directory   when  sensors  are  brought  online   •  A  crawler  can  discover  links  at  ./well-­‐known/core   locaJons  and  populate  catalogs   •  ApplicaJon  soTware  can  discover  resources  by   aribute,  e.g.  query  using  type=‘temperature’,   units=‘celsius’,  locaJon=‘outdoor’  etc.     •  System  returns  a  set  of  links  matching  the  query   aributes  
  • 7. CoAP   •  Part  of  IPV6  for  Constrained  Resource   Environments  (CoRE)   •  IoT  oriented  REST  API  mapped  to  an  efficient   binary  protocol   •  End  devices  can  have  both  client  and  server   roles,  can  also  communicate  directly   •  Resource  representaJon  e.g.  ‘applicaJon/ json’,  is  negoJated  as  in  hp  protocol  
  • 8. CoAP   •  Observe  opJon  for  long-­‐term  event  stream   response  to  GET,  asynchronous  updates   •  Web  linking  using  IETF  standard  core-­‐link-­‐ format  (RFC  6690)   •  Resource  discovery  using  ./well-­‐known/core   or  external  Resource  Directory    
  • 9. HTTP/REST   •  HTTP  and  REST  is  useful  for  most  web   applicaJons,  services,  and  gateways   •  Uses  web  callbacks,  websockets,  HTTP  PUT  for   asynchronous  updates   •  Links  in  JSON,  Link-­‐format,  Hypercat,  linked   data   •  Well  defined  CoAP-­‐to-­‐HTTP  proxy  paerns,   standard  middleware  
  • 10. Hybrid  system   •  It’s  possible  to  use  REST  for  resource  discovery   and  other  stateful  interacJons,  and  messaging   e.g.  MQTT  for  asynchronous  updates   •  Various  methods  to  bind  message  endpoints   to  REST  resources   •  ApplicaJon  soTware  can  easily  use  both  REST   API  and  event  handler  interfaces  like   onUpdate   •  IoT  Toolkit  uses  observers  to  bind    
  • 11. Standards  and  SoTware   •  CoAP     hps://datatracker.iel.org/doc/draT-­‐iel-­‐core-­‐coap/   •  CoRE  link-­‐format   hp://tools.iel.org/html/rfc6690   •  CoRE  Observe   hps://datatracker.iel.org/doc/draT-­‐iel-­‐core-­‐observe/   •  CoRE  Resource  Directory   hps://tools.iel.org/html/draT-­‐iel-­‐core-­‐resource-­‐directory-­‐00   •  Hypercat   hp://wiki.1248.io/doku.php?id=hypercat  
  • 12. IoT  Toolkit  Interoperability  Demo   smartobjectservice.com   Node-­‐RED   Node-­‐RED  
  • 13. MQTT  Observer   MQTT  Broker   REST  Endpoint   ObservableProperty   mqObserver   PUT   GET   Publish  from   data  producer   Publish  From   REST  API   Publish  to  Other   Subscribers   SUB   Publish  to   REST  API     Connects  REST  Resource  to  MQTT  Topic   Publish  and  Subscribe  
  • 14. MQTT  Observer   MQTT  Broker   REST  Endpoint   ObservableProperty   mqObserver   PUT   GET   Publish  from   data  producer   Publish  From   REST  API   Publish  to  Other   Subscribers   SUB   Publish  to   REST  API     Publisher     Publishes  REST  Resource  updates  to  the  broker  
  • 15. MQTT  Observer   MQTT  Broker   REST  Endpoint   ObservableProperty   mqObserver   PUT   GET   Publish  from   data  producer   Publish  From   REST  API   Publish  to  Other   Subscribers   SUB   Publish  to   REST  API     Subscriber     Makes  last  published  data  available  at  the  REST  endpoint  
  • 16. MQTT  Observer   MQTT  Broker   REST  Endpoint   ObservableProperty   mqObserver   PUT   GET   Publish  from   data  producer   Publish  From   REST  API   Publish  to  Other   Subscribers   SUB   Publish  to   REST  API     Pub+Sub   Repeats  data  updates  in  both  direcJons  
  • 17. MQTT  Bridge  to  mulJple  REST  endpoints     MQTT  Broker   REST  Endpoint   ObservableProperty   mqObserver   PUT   GET   Publish  from   data  producer   Publish  to  Other   Subscribers   REST  Endpoint   ObservableProperty   mqObserver   PUT   GET  

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