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https://issues.apache.org/jira/browse/FLINK-6418?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dawid Wysakowicz reassigned FLINK-6418:
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Assignee: Dawid Wysakowicz
> Support for dynamic state changes in CEP patterns
> -------------------------------------------------
>
> Key: FLINK-6418
> URL: https://issues.apache.org/jira/browse/FLINK-6418
> Project: Flink
> Issue Type: Improvement
> Components: CEP
> Affects Versions: 1.3.0
> Reporter: Elias Levy
> Assignee: Dawid Wysakowicz
>
> Flink CEP library allows one to define event pattern to match where the match
> condition can be determined programmatically via the {{where}} method. Flink
> 1.3 will introduce so-called iterative conditions, which allow the predicate
> to look up events already matched by the pattern and thus be conditional on
> them.
> 1.3 also introduces to the API quantifer methods which allow one to
> declaratively specific how many times a condition must be matched before
> there is a state change.
> Alas, there are use cases where the quantifier must be determined dynamically
> based on the events matched by the pattern so far. Therefore, I propose the
> adding of a new {{Pattern}}: {{until}}.
> Like the new iterative variant of {{where}}, {{until}} would take a predicate
> function and a context that provides access to events already matched. But
> whereas {{where}} determines if an event is accepted by the pattern,
> {{until}} determines whether is pattern should move on to the next state.
> In our particular use case, we have a pattern where an event is matched a
> number of times, but depending on the event type, the number (threshold) for
> the pattern to match is different. We could decompose the pattern into
> multiple similar patterns, but that could be inefficient if we have many such
> patterns. If the functionality of {{until}} were available, we could make do
> with a single pattern.
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