Sequence matching semantics in Flink CEP

0
votes

There is an issue in Apache JIRA: https://issues.apache.org/jira/browse/FLINK-3703. It allows defining where the matching algorithm should continue after a matching sequence has been found and there are three types of behavior:

  • from first - continue keeping all events for future matches (that is the current behavior)
  • after first - continue after the first element (remove first matching event and continue with the second event)
  • after last - continue after the last element (effectively discarding all elements of the matching sequence)

For example, if we have a sequence of events: A, B, C and pattern first -> second we'll get next results:

  • from first - A -> B, A -> C, B -> C
  • after first - A -> B, B -> C
  • after last - A -> B

Now the issue is closed with a comment that all of that implemented in other tasks:

This was covered by other issues including the Quantifier implementation, the skip-till-next and some additional issues for continuity within looping patterns.

So, could somebody tell me how to implement defined kinds of behavior using current API of the Flink CEP library?

1
javascalaapache-flinkcomplex-event-processingflink-cep

1 Answers

0
votes

I've found the answer to my question and I'd like to share this information: the behavior how the matching algorithm should continue after a matching sequence has been found can be defined by AfterMatchSkipStrategy. But, it works only since version 1.4. Well, we're waiting for the release.

Here is more information: https://ci.apache.org/projects/flink/flink-docs-release-1.4/dev/libs/cep.html#after-match-skip-strategy.