Modify attribute on device by IOT-Agent Json

Question

I am using IOT-agent JSON with MQTT binding

I have a sensor-actuator registered in orion using iot-agent and I created the subscription.

If a third party application modifies a sensor value, orion must send iot-agent information and iot-agent to the device.

for example, if I have 3 attributes inside the sensor and one of them controls a valve.

In orion that attribute is true or false.

if the attribute is modified in orion must be sent to iot-agent and iot-agent to the device to close or open the valve.

extra information:

The software is two component of Fiware Generic Enable.

iot-agent JSON: https://github.com/telefonicaid/iotagent-json Fiware-orionCB: https://github.com/telefonicaid/fiware-orion

Is it possible?

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Jason Fox Jason Fox · Accepted Answer · 2018-10-04T09:36:17

There is no official tutorial connecting the JSON IoT Agent to a device over MQTT, but a very similar one exists for the Ultralight IoT Agent

IoT Devices are either:

sensors - reading measurements from the real world
actuators - altering the state of the world
or both

Your issue here is that you cannot get Orion to update the attribute/state of a sensor directly. The attributes of the entity in the Context Broker represent the incoming state of the sensor - i.e. the measurements from that sensor.

For example for the sensor reading the state of a valve it could be "open: "true"

In order to update an actuator, you will need to send a command, rather than alter the value.

You should set up the command when provisioning the device (it is assumed you have a service already):

curl -iX POST \
  'http://localhost:4041/iot/devices' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "devices": [
    {
      "device_id": "bell001",
      "entity_name": "urn:ngsi-ld:Bell:001",
      "entity_type": "Bell",
      "protocol": "PDI-IoTA-UltraLight",
      "transport": "MQTT",
      "commands": [
        { "name": "ring", "type": "command" }
       ],
       "static_attributes": [
         {"name":"refStore", "type": "Relationship","value": "urn:ngsi-ld:Store:001"}
      ]
    }
  ]
}
'

You can then send the command to do something (like ring a bell, open a valve etc.) by altering the state of the command attribute.

curl -iX PATCH \
  'http://localhost:1026/v2/entities/urn:ngsi-ld:Bell:001/attrs' \
  -H 'Content-Type: application/json' \
  -H 'fiware-service: openiot' \
  -H 'fiware-servicepath: /' \
  -d '{
  "ring": {
      "type" : "command",
      "value" : ""
  }
}'

Depending upon how you have provisioned devices, you may also need to register the command - though this may not be necessary.

Modify attribute on device by IOT-Agent Json

1 Answers