Proton CEP Fiware: delete old received events

Question

I've got this kind of problem with Proton CEP: i currently have a "Sequence" EPA; its input are 2 events. But these events have different granularity: let's say i have A and B events; i receive N "A" events, and M "B" events, where M << N. So i'd like to have a rule like "if event of type A is not consumed within X seconds, remove it", otherwise i've got a long A events queue; i only need the rule to be evaluated for closest (temporally) events. Practically, i've got a fake room temperature sensor that sends its temperature updates every 5seconds, and i've got another program that checks external weather and sends it every minute.

Any idea how to solve this situation?

Thank you very much!

Answer 1

I guess that in "consume" you mean arrival, so do you want to evaluate the time the A event took to get to the proton pcoressor? or the time between A events? Do you want to ensure that the A events are indeed continuous in a fix rate? "Removing" an event means to ignore it, since events are not kept anywhere, just processed. At the end, what is that you want to detect here? Like, what is the trend of room temperature compared to the outside temperature? then, emit output events accordingly?

Thanks.

Answer 2

all the relevant event instances are kept within the local state of a corresponding EPA. For each EPA operand you have policies which dictates how the state is gathered and how the matching set for event derivation is built. For example, instance selection policy which is defined per operand, and has the values of "Each", "First" and "Last" will tell you if all A instances are examined for match with B instance, or the first (in the order of arrival), or the last. The consumption policy says what to do with the operand state once a seqence is detected - should the instances of say A which participated in sequence be removed from EPA's state ("consume" value of the policy) or should they remain.

Playing with combination of those policies should give you the behaviour you require