IoT development needs in the back-end

• APIs optimized for the web
• control who has access to which aspects
• directly communicate to devices and access last known state
• get notified about changes/events
• enhance APIs with further functionality

sounds complicated?

let's find out if the Digital Twin pattern can help

Digital Twin metaphor

• mirrors physical devices
• provider of aspects+services around devices
• keep real and digital worlds in sync
• applicable for both industrial and consumer-centric IoT scenarios

in IIoT / Industry 4.0

• asset administration shell ("Verwaltungsschale")
• holistic view of all capabilities (services) and aspects of an asset

Source

in context

domain model

• how does the model of Eclipse Ditto look like?
• KISS

turn device data into API

{
  "thingId": "namespace:car-1",
  "acl": { ... },
  "attributes": {
    "manufacturer": "ACME corp",
    "productionData": {
      "serialNo": 4711
    }
  },
  "features": {
    "headlights": {
      "properties": {
        "on": false
      }
    }
  }
}

GET/PUT/DELETE /api/1/things/namespace:car-1
 /api/1/things/namespace:car-1/thingId
 /api/1/things/namespace:car-1/acl
 /api/1/things/namespace:car-1/attributes
 /api/1/things/namespace:car-1/attributes/manufacturer
 /api/1/things/namespace:car-1/attributes/productionData
 /api/1/things/namespace:car-1/attributes/productionData/serialNo


 /api/1/things/namespace:car-1/features
 /api/1/things/namespace:car-1/features/headlights
 /api/1/things/namespace:car-1/features/headlights/properties
 /api/1/things/namespace:car-1/features/headlights/properties/on

Ditto Protocol API

• JSON based text protocol for communicating with Digital Twins bidirectionally (commands/events)
• via: WebSocket, AMQP 1.0 (e.g. Hono), AMQP 0.9.1

{
  "topic": "namespace/car-1/things/twin/events/modified",
  "headers": { ... },
  "path": "/features/headlights/properties",
  "value": {
    "on": true
  },
  "revision": 42
}

access control

"acl": {
  "ditto": {
    "READ": true,
    "WRITE": false,
    "ADMINISTRATE": false
  },
  "adam": {
    "READ": true,
    "WRITE": true,
    "ADMINISTRATE": true
  }
}

{
  "policyId": "namespace:car-1-policy",
  "entries": {
    "owner": {
      "subjects": {
        "nginx:admin": {
          "type": "nginx basic auth user"
        }
      },
      "resources": {
        "thing:/": {
          "grant": ["READ","WRITE"],
          "revoke": []
        },
        "thing:/features/firmware": {
          "grant": [],
          "revoke": ["WRITE"]
        },
        "policy:/": {
          "grant": ["READ","WRITE"],
          "revoke": []
        }
      }
    }
  }
}

twin vs. live

• uses Ditto as persistence
• Ditto enforces access control
• Ditto processes commands, emits events

• uses Ditto as router
• Ditto enforces access control
• endpoints process commands, emit events

→ docs

get notified about changes

var ws = new WebSocket(
  "ws://u:p@ditto.eclipseprojects.io/ws/1");
ws.onopen = function(w) {
  w.send('START-SEND-EVENTS');
};
ws.onmessage = function(msg) {
  console.log('received: ' + msg.data);
};

var source = new EventSource(
  "/api/1/things?ids=namespace:car-1");
source.onmessage = function(msg) {
  console.log('received: ' + msg.data);
};

search

• you must not
• Ditto has you covered

GET /api/1/search/things
  ?filter=like(attributes/manufacturer,"ACME*")

GET /api/1/search/things
  ?filter=and(
    exists(attributes/manufacturer),
    eq(features/headlights/properties/on,true)
  )
  &namespaces=org.eclipse.ditto
  &option=sort(-attributes/manufacturer)
  &fields=thingId,attributes/manufacturer,_modified

nonfunctional

orchestration via messages

• enhance the API of a Digital Twin by a custom WebSocket consumer

examples for orchestrations

• enhance a location-aware Twin with the current weather
• enhance a Twin with an API for its known spare parts

Roadmap 2018

• release (non-milestone)
• using Eclipse Vorto generator for validation
• mapping raw payloads to/from Ditto Protocol
• attracting IoT developers in using Ditto
• integration with other OSS projects