Hi and sorry for a delayed answer 🙂

Please, can you clarify what you mean with “aggregate notifications like Datachange and Event Notification”? It could mean several different things. In UA you will create Subscriptions in which you add MonitoredItems. MonitoredItems will receive notifications based on the MonitoringFilter set to the item. There are currently 3 different filters: DataChangeFilter, EventFilter and AggregateFilter.

For Events, the EventFilter is used to define which event fields are sent back and in which order.

For Values, the DataChangeFilter and AggregateFilter can be used. DataChangeFilter is the normal and widely used one. It can be set to trigger on updates according to a chosen mode (Status, Status+Value, Status+Value+Timestamp) and optionally to include a deadband. AggregateFilter can be used instead to calculate Aggregates for the data on the server side. However, you should note that many servers do not support AggregateFilters for Subscriptions.