I use subscribeAsync to subscribe to tag value change.
My module run on a frontend redundant gateway and I subscribe remote tags on a backend redundant gateway.
Subscribe is done on gateway startup script and unsubscribe in the gateway shutdown script.
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I don't know if I need to manage something from my side in the module when there is a backend failover ?
or Ignition subscribeAsync implementation manage automatically subscription on the new active node ?
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I don't know if I need to manage something from my side in the module if when I subscribe the backend gateways are not connected to the frontend ?
or Ignition subscribeAsync implementation automatically notify resend the request when the node is again available ?
A question probably for @mgross !
I'm not sure if your custom subscription code would change anything, but with normal remote tag subscriptions, it should be able to figure out that the remote master is down, and automatically switch to the remote backup. In that case, you get a log message like this on your gateway that runs the remote subscription:
controller-1 | jvm 1 | 2026/05/18 06:17:41 | I [m.M.Routing ] [06:17:41.853]: Changing target route for redundant server 'agent' to 'Backup' (forced=false)
Similarly, if both gateways are down, the gateway that runs the remote subscription should automatically re-establish itself after the gateway has reconnected to one of the redundant remote gateways. In that case, you get a log message like this:
controller-1 | jvm 1 | 2026/05/18 06:10:39 | W [G.R.T.SubscriptionManager ] [06:10:39.068]: [agent] Subscription path model set detected to be out of sync. Will re-synchronize.
That's perfect !
Thanks a lot for these clarification.
I start to test and the subscription mecanism is redundancy and disconnection aware.