In context of Event Management (including the notification model in each TMF API), the Event object contains the target entity value at the moment of the event; so in the Event model we have information about the target entity only as event consequence, but we don't have the previous values of the entity.
E.g: as you can see in the screenshot below (example from the user guide v.4.0.0), you have the target entity "alarm" defined with the values as consequence of the event occurred, but in case of eventType like AttributeValueChangeEvent there is not the possibility to pass,as part of event model, the previous attributes values (the "alarm" values before that the event occurred).

Based on what we understood should be eventually the consumer of this event to have stored the previous entity state (the previous entity attribute values) and we can't support a stateless consumer that will process an event in case of "AttributeValueChangeEvent" or "StateChangeEvent".
Are our assumption right and did you discuss how to handle in event model the previous status/values of the entity?
Thanks and regards,
Luca
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Luca Icardi
Accenture
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