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Alarm subscription and the Alarm web service

Sep 20, 2012 at 3:38 PM

Are alarm subscriptions and the Alarm web service in 'sync'? That is, are they both totally consistent in time? A scenario:

1. An alarm 'X' is raised

2. an application subscribes to the alarm 'X' 1 millisecond after the alarm is raised. I assume that no message will be sent for the previous raising.

3. Immediately upon success in the subscription, the web service is accessed.

 

Will step 3 ALWAYS return the raised alarm. My worry is that the web service might be part of the historian subsystem, a little out of sync with the real-time alarms. I assume that this is safe, but thought I'd better ask.

Sep 20, 2012 at 8:23 PM

Yes, in this scenario, step 3 will always return the raised alarm. The web service does not access the historian subsystem, so no worries there.