Realtime alarms without polling/looping vs event based alarms

Ignition
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1

Hello,
currently there are essentially two methods, that I know of, to retrieve active alarms:

querying the db, i.e.: " SELECT * FROM alarm_events" with a fixed polling time

looping with a python script, i.e. " system.alarm.queryStatus()" and then sleeping in between or similar.

both of these methods are looping/polling methods and they are quite expensive (we use the db polling at the moment with a 5 minutes delay and we are quickly reaching millions of queries per hour on each of our Aurora RDS cluster).

Is there some event based / subscription method for fetching alarms which is less taxing and more realtime? something like system.alarm.subscribe(tag_path) which fires when an alarm is ever raised or reenters?

Thank you

2

You can call scripts from alarm pipelines and cache the information.

3

We are experimenting with something similar however the solution is not very robust:

  • we need to define a pipeline for all alarms
  • we need to define the pipeline for the raise, acked and entered states
  • we must store a last-executed time in a memory tag to avoid consecutive alarms from trashing the server.
  • we must create a polling gateway event to execute all this logic every 1 minute.

I hoped perspective / ignition offered something more realtime and event oriented.

4

Not from inside the Ignition runtime, but it’s possible using the module SDK to register a listener that receives active, clear, and acknowledge notification for events as they occur.

5

Thank you for the response. I’ll take a look at the SDK.