Send a command to multiple devices in Google Cloud IoT Core with MQTT

Question

How can I send a command to all the devices in a registry using MQTT and Google Cloud IoT Core?

All the examples I've seen till now just send the command to a single device. Do I have to loop on my devices and send a message to each of them?

Thanks in advance.

Have you tried using an MQTT wildcard (I think it's the hash '#') in the device-id field? — Carl Rossman
– Carl Rossman, Commented Apr 27, 2019 at 13:45

Misha Brukman · Accepted Answer · 2019-03-21 15:41:48Z

2

You would need to list devices in a registry, and then call the sendCommandToDevice method in a loop as you suggested.

For reference, it would look something like this (in Python):

command = '{ "state": "off" }'
registry_path = 'projects/{}/locations/{}/registries/{}'.format(
    project_id, cloud_region, registry_id)

client = get_client(service_account_json)
devices = client.projects().locations().registries().devices(
    ).list(parent=registry_path).execute().get('devices', [])

for device in devices:
  device_path = 'projects/{}/locations/{}/registries/{}/devices/{}'.format(
      project_id, cloud_region, registry_id, device.get('id'))

  config_body = {
    'binaryData': base64.urlsafe_b64encode(
      command.encode('utf-8')).decode('ascii')
  }

  client.projects().locations().registries().devices().sendCommandToDevice(
      name=device_path, body=config_body).execute()

edited Mar 21, 2019 at 15:41

Misha Brukman

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answered Mar 20, 2019 at 21:27

Alex Hong

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