Unsubscribing from a subscription on form close

[phuz]

I couldn't find a relevant thread on this, so if it does exist, my apologies.

I understand that unsubscribing on close is a form of good housekeeping, but is it necessary?  If so, must you loop through each unique ID or is there a method to just dispose of all active subscriptions?

I mean, sure it's very simple...just wondering how necessary it is.

Code: [Select]

        While subscriptionID > 0
            mainplc.UnSubscribe(subscriptionID)
            subscriptionID = subscriptionID - 1
        End While

[Archie]

If a form is closed with a driver instance on it, all of the subscriptions are terminated automatically. This is because subscriptions live in the driver instance and not in the backend DLL. So closing a form disposes the driver instance, which in turn deletes all subscriptions

[phuz]

I assume the same is true if driver is initialized in a service application instead of a form?

[Archie]

If you are doing all code, it is up to you to properly handle disposing of driver instances. Otherwise the subscription threads will continue to run.

[phuz]

Would it be sufficient to say "EthernetCLXDriver.DisableSubscriptions = True" on form close and call it a day?

[Archie]

DisableSubcriptions only pauses the update process. It does not shut down the subscriptions threads

[phuz]

Is there a way to get a list of all active subscriptions?

[Archie]

I don't think there is a way to expose the list of active subscriptions. It is really up to you to keep a list of the subscription IDs.

If you want to unsubscribe from them all, a hack you can use is to create a new subscription to get the latest ID. The use a loop from 0 to the latest ID to call Unsubscribe on each ID