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Designing an API for the Internet of Things
Kevin Swiber
Overview
Ubiquitous Computing
Like control systems
Sensor Actuator
Controller
Environment
The Internet
…but on the Internet
More than 50B connected devices by 2020
Maturity Scale
The Web
Mobile
Things
3 Models of Connectivity
The Hub
DevicesDevicesDevices
Hub
Cloud Components
DevicesDevicesDevices
Hub
ClientsClientsClients
ClientsClientsClients Local Network
Data Center
Internet
The Bridge
DevicesDevicesDevices
Bridge
Cloud Components
DevicesDevicesDevices
Bridge
ClientsClientsClients
Local Network
Data Center
Internet
The IP-Connected Device
Device
Cloud Components
Device
ClientsClientsClients
Local Network
Data Center
Internet
APIs Suck
/data.cgi
/data.cgiN00BIE
.NET Remoting
.NET RemotingBROKEN
SOAP
SOAPSTUPID
RESTful?
RESTful?WRONG
Hypermedia!
Hypermedia!NERD
What’s the problem?
The real world is complex
Feedback can be vicious
We fool ourselves into thinking all problems are the same
There is no silver bullet
Love the bomb
The 15th Standard
Back to Zetta (IoT)
Reaching the Edge
DevicesDevicesDevices
Zetta
Zetta
DevicesDevicesDevices
Zetta
ClientsClientsClients
ClientsClientsClients Local Network
Data Center
Internet
The only thing we control
Desired Architectural Properties
• Decoupling of implementations
• Independent evolution
• Scale
• Load balancing
• Centralize complexity, distribute simplicity
• Reduce latency
• Support event streams
Architectural Constraints• Client-server, stateless, cacheable, layered
system, uniform interface, etc.
Wait, isn’t that REST?
What about event streams?
How streams are done over HTTP today
• WebHooks
• Chunked Transfer-Encoding
• HTTP Pipelining
• Long Polling
• Server Sent Events
XXXXX
Just upgrade
Connection info is in the action parameters or link URI
• mqtt://example.org:8863/topic
• stomp+ws://example.org/topic
• amqp://example.org/topic • { “href”: “ws://example.org”, “protocol”: “custom” }
It works!
Model resources as finite state machines
LED.prototype.init = function(config) { config .type('led') .state('off') .when('off', { allow: ['turn-on'] }) .when('on', { allow: ['turn-off'] }) .map('turn-on', this.turnOn) .map('turn-off', this.turnOff); };
Transitions are represented as affordances in the message.
"actions": [ { "name": "turn-on", "method": "POST", "href": “...”, "fields": [ { "name": "action", "type": "hidden", "value": "turn-on" } ] } ]
We need to consume an object stream.
links: [ { title: “pulse“, rel: [“http://rxapi.org/object-stream“], href: “ws://...” } ]
We need to consume an object stream.
» wscat -c ws://... connected (press CTRL+C to quit) < {"topic":"heartbeat/1/pulse","timestamp":1411757412119,"data":61} < {"topic":"heartbeat/1/pulse","timestamp":1411757412620,"data":65} < {"topic":"heartbeat/1/pulse","timestamp":1411757413121,"data":69} < {"topic":"heartbeat/1/pulse","timestamp":1411757413622,"data":71} < {"topic":"heartbeat/1/pulse","timestamp":1411757414124,"data":66} < {"topic":"heartbeat/1/pulse","timestamp":1411757414626,"data":64} < {"topic":"heartbeat/1/pulse","timestamp":1411757415128,"data":68} < {"topic":"heartbeat/1/pulse","timestamp":1411757415629,"data":63} < {"topic":"heartbeat/1/pulse","timestamp":1411757416130,"data":65} < {"topic":"heartbeat/1/pulse","timestamp":1411757416631,"data":63}
Monitor resource events before taking action.
links: [ { title: “logs“, rel: [ “monitor“, “http://rxapi.org/object-stream“ ], href: “ws://...” } ]
Monitor resource events before taking action.
» wscat -c ws://... connected (press CTRL+C to quit) < {"topic":"led/2/logs","timestamp":1411809676901,"transition":"turn-on","input":[],"properties":{"id":"2","type":"led","name":null,"state":"on"}} < {"topic":"led/2/logs","timestamp":1411809677548,"transition":"turn-off","input":[],"properties":{"id":"2","type":"led","name":null,"state":"off"}} < {"topic":"led/2/logs","timestamp":1411809678483,"transition":"turn-on","input":[],"properties":{"id":"2","type":"led","name":null,"state":"on"}} < {"topic":"led/2/logs","timestamp":1411809679126,"transition":"turn-off","input":[],"properties":{"id":"2","type":"led","name":null,"state":"off"}}
We also need binary.
links: [ { rel: [“http://rxapi.org/binary-stream“], href: “ws://...“, type: “video/mpeg“, } ]
We also need binary.
» wscat -c ws://... connected (press CTRL+C to quit) Q`rCEDˌDIp=`"3ss79:Yk}{` 5e\`>9%J[K89\z^> 8X Gp;W̮qXF h1{%O;7<Biڞ.r r5 vyeK[X@ƯDRmT:uLz[�V .vK",,u!N8 ֝=LQ=s~ӆ`]{E6[ WȝM]3Uo|&n Њmo('/K>2칩e,l{%`:<rtN|SXu曆psFJS*s#AB]ý0Rt_`uS}vX3ctA>kJfuΎ^L๖ V"u8GU*ڹ
We also need binary.
» wscat -c ws://... connected (press CTRL+C to quit)
Reactive Clientsvar siren = require('siren');
siren() .load('http://zetta-cloud-2.herokuapp.com') .link('http://rels.zettajs.io/peer', 'Detroit') .entity(function(e) { return e.properties.type === 'sound'; }) .link('http://rels.zettajs.io/object-stream', 'level') .monitor() .subscribe(console.log);
Reactive Clientsvar zrx = require('zrx');
zrx() .load('http://zetta-cloud-2.herokuapp.com') .server('Detroit') .device(function(d) { return d.type === 'sound'; }) .stream('level') .subscribe(console.log);
Reactive Stream Control Protocol
• Consumer controlled streams
• Runs over WebSockets
• Multiplex streams
What can you do with streams?
• Monitoring values over time
• Distributed data processing
• Event sourcing
• Batches
Going Forward
// TODO:
• Extract reactive hypermedia framework from Zetta internals.
• Produce a clean specification and documentation.
• Experiment with multiple languages/platform implementations.
Additional Topics• Managing device identity
• Security along the entire stack
• Working in an occasionally connected environment
• Working with highly constrained devices
• Enterprise IoT
Hit me up!• [email protected]
• https://twitter.com/kevinswiber
• https://linkedin.com/in/kevinswiber
• https://github.com/kevinswiber
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