Subscribing to Device Online or Offline Status

Developer Programs
2

You could create a schedule to make the request to /devices/<deviceId>/health and when the device is offline, send the event to DeviceWatch-DeviceStatus.
For you to take control over the DeviceWatch events, you need to enroll as follows:

//initialize
sendEvent(name: "DeviceWatch-DeviceStatus", value: "online")
sendEvent(name: "DeviceWatch-Enroll", value: [protocol: "cloud", scheme:"untracked"].encodeAsJson(), displayed: false)

//event to change the deviceStatus
sendEvent(name: "DeviceWatch-DeviceStatus", value: "offline")

Then, to create the subscription for a specific device health you’ll have to use that attribute.

context.api.subscriptions.subscribeToDevices(deviceConfig, 'healthCheck', 'DeviceWatch-DeviceStatus', 'healthEventHandler')

//payload example
{
  eventId: 'xxxx-xxxx-xxxx',
  locationId: 'xxxx-xxxx-xxxx',
  ownerId: 'xxxx-xxxx-xxxx',
  ownerType: 'LOCATION',
  deviceId: 'xxxx-xxxx-xxxx',
  componentId: 'main',
  capability: 'healthCheck',
  attribute: 'DeviceWatch-DeviceStatus',
  value: 'offline',
  valueType: 'string',
  stateChange: true,
  data: {},
  subscriptionName: 'healthEventHandler_0'
}

Or, you can use the health subscription part of the SDK, this is at a location level, so, you will receive the events from all the devices in it.

context.api.subscriptions.subscribeToDeviceHealth('healthEventHandler')

//eventHandler
.subscribedDeviceHealthEventHandler('healthEventHandler', (context, event) => {  })

//payload example
{
  eventId: 'xxxx-xxxx-xxxx',
  locationId: 'xxxx-xxxx-xxxx',
  deviceId: 'xxxx-xxxx-xxxx',
  hubId: 'xxxx-xxxx-xxxx',
  status: 'ONLINE',
  reason: 'NONE'
}