Our API for reading historical values is compatible with the OPC UA specification. But sometimes we get requirements from clients, which are not covered by 10000-01 Historical Access.
One of these is: read raw data of a time range, then filter this raw data according to certain criteria, then apply the aggregate processing on that filtered raw data.
In our specific case the client logs states (as integer values) and wants to know, how often the this node changed to a specific state in an interval, or how long the node stayed in a specific state. Additionally, the filter should consider a set of states, or all states except a set of states.
Could this be of interest for a wider range of applications and therefore for OPC UA ?