Heartbeat MQTT message about openeew-sensor

[andygrillo]

Doesnt the MQTT broker automatically track devices that are connected to it ? isnt there an inbuilt heartbeat that is used by MQTT which we can simply read from node-red ?

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On Thu, 10 Dec 2020 at 15:40, John Walicki ***@***.***> wrote: Today, the sensor sends a MQTT message every second that contains accelerometer data. If we're getting data, we know the board is alive. If we implement an edge based STA / LTA algorithm, the sensor will process the accelerometer data at the edge. If there are no earthquakes, we might not hear from a board for weeks/months. We won't know its alive. When we implement STA/LTA edge processing, we should also implement a heartbeat MQTT topic to replace the MQTT data. It does not need to be every second. The MQTT message would only need to send 1 byte of data. We can derive the macaddress from the device id (part of the Watson IoT headers). In the cloud, we could either update the Cloudant record with a last heartbeat timestamp. The OpenEEW dashboard could read that to indicate status. There's a Watson IoT Last Event rest api but the dashboard would need to know those credentials. I could find an example of that implementation too. Maybe once a minute - would be 1440 messages/day Maybe once a hour - would be 24 messages/day If we're worried about the IBM Cloud Watson IoT Platform lite tier, its limited to 200MB/month so we would want to keep our heartbeats small / sufficiently infrequent. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#57>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABP5GHLYKHL5JWNIPQAHAFDSUE56PANCNFSM4UVURKEQ> .

-- Andres Meira *m* [phone] *skype *andresmeira

[johnwalicki]

Yes, Possibly. There is a Node-RED node to query the status of a device. I have a flow which can enumerate all of the devices. It then can iterate across all the devices and get status for each one. I've never used that technique as a heartbeat. Will need to experiment to see if I can discover if they are up/down

I see:
payload.status.alert.enabled is either true or false
payload.status.alert.timestamp

[johnwalicki]

There are other techniques to get the MQTT status of a device. Will implement this for the OpenEEW Dashboard in a different way. Saves sending useless messages to the cloud. Closing ticket.