providing context for next condition

Question

I want to detect all sequences of the same integer that is followed by the count of these integers. is there any way to create this pattern with the Flink CEP library? suppose this:

val input List(1,2,2,2,3,3,2,1,1,1,3,0,1)

these sequences should be detected:

List(2,2,2,3)
List(3,3,2)
List(1,1,1)

I know there are many ways to do it by the Flink itself but I want to do it with CEP and I think it needs support passing context to the next condition am I right? if so, is it possible with Flink CEP to pass context or modify the events on stream and put some extra data to pass information to the next condition?

score 1 · Accepted Answer · answered Sep 11 '22 at 18:33

1

is it possible with Flink CEP to pass context or modify the events on stream and put some extra data to pass information to the next condition?

Flink CEP supports iterative conditions, which are conditions that can examine the events that matched earlier components of a compound pattern. I think that's powerful enough to handle this use case.

There's an example showing how to use iterative conditions in one of the recipes in the Immerok Cookbook: Alerting when Problems Persist.

(Disclaimer: I work for Immerok.)

answered Sep 11 '22 at 18:33

David Anderson

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god bless you and Immerok. – Mohammad Reza Esmaeilzadeh Sep 12 '22 at 11:29
can we use the context of multiple previous patterns on we are only limited to one? – Mohammad Reza Esmaeilzadeh Sep 12 '22 at 11:41
You can look back at any or all of the earlier components of the current pattern. – David Anderson Sep 12 '22 at 12:27
See https://github.com/immerok/recipes/blob/main/pattern-matching-cep/src/main/java/com/immerok/cookbook/conditions/StillHotLater.java#L23 -- you specify the component sub-pattern by name, and get back an iterator for the events that matched that part of the pattern. – David Anderson Sep 12 '22 at 12:50

providing context for next condition

1 Answers1