Should the aggregation be over multiple values in the past or just some aggregation of = last_valueA + last_value_B .... ? For the first case, i recommend using a standalone togehter with a memory cache. For a more robust setup, i would suggest using a database e.g Timescale and then in the processing part execute an SQL to the wanted tags you want to aggregate. And for the second option you could use a stream, but be awear that if any value changes in A, B or C the aggregation will get triggerd, so maybe also have to use a standalone for this (memory cache)