OPC-UA Listener plugin support for MonitoringFilter (DataChangeFilter)

[JohnArneBirkeland]

Use Case

When subscribing to OPC-UA nodes, and integral part of this subscription model is to assign a MonitoringFilter to the subscriptions.

These filters are used to define the conditions (typically how much a value must change using a DataChangeFilter) for when the server should generate a DataChangeNotification.

This is essential for managing the subscription data flow in larger industrial systems with thousands of sensors.
Specifically being able to use the DataChangeFilter to specify how much a value must change before subscription data is sent, is critical in systems where analog sensors may generate non-stop high frequency changes without this filter.

Expected behavior

The client subscription model should expose the MonitoringFilter part of OPC-UA so that filter parameters can be set and modified.

Actual behavior

MonitorFilter is not yet implemented.

Additional info

OPC-UA Reference documentation:
https://reference.opcfoundation.org/Core/Part4/v104/docs/7.17

[powersj]

@magichair & @LarsStegman,

Is adding a filter like datachangefilter or monitoringfilter possible to the OPC-UA listener plugin? Does this support exist in the goopcua library such that we can make sure of it?

Thanks!

[LarsStegman]

This issue was related to this comment: #8083 (comment)

Yes, the library has it and it shouldn't be too much work to add the functionality to Telegraf I think.