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Determine active subscriptions

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08 Dec 2015 13:59 #3720 by support
The first part can be achieved by maintaining a list of what you have subscribed to on your side (in one common storage), as it is completely under your control.

Not sure what you mean by the second part. If you refer to some kind of error handling, then be careful with that, and read the documentation first. In QuickOPC, a "subscribe" call indicates a permanent intent to become and stay subscribed - valid until a corresponding "unsubscribe" is called. In case of any errors, you will still receive a valid subscription handle. You just get an error notification (event or callback), and after a configurable period, QuickOPC will attempt to subscribe again - and so on. This approach automatically handles reconnections in case of errors caused e.g. by temporary network or server failures, server restarts, transient server misconfigurations, etc.

Best regards

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  • Romaco123
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08 Dec 2015 12:06 #3719 by Romaco123
Replied by Romaco123 on topic Determine active subscriptions
To optimize the Performance of our App we've decided to activate and deactive Variables in Groups. The Activation can be invoked async by different Tasks. It would be helpfull for us to have a Method to (pre)check if/which Variables/Groups are activated before invoking a (new) subscription.
The other reason is to be sure that all the Variables in the List (when calling SubscribeMultple..) were actually succesfully subscribed (or some were not).

Thank you
Best Regards

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08 Dec 2015 10:49 #3718 by support
Not really, but please describe your use case (what are you trying to achieve), and I should be able to help you. Normally, such method should not be needed.

Best regards

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08 Dec 2015 07:54 #3717 by Romaco123
Determine active subscriptions was created by Romaco123
Is there a Method available to retrieve a List of the currently active Variable-Subscriptions?

Thx

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