# Best practice for filtering Kafka messages before process instance creation

**URL:** <https://forum.flowable.org/t/best-practice-for-filtering-kafka-messages-before-process-instance-creation/12579>\
**Category:** Flowable Engine\
**Created:** [June 5, 2026, 10:41am UTC](https://forum.flowable.org/t/best-practice-for-filtering-kafka-messages-before-process-instance-creation/12579 "2026-06-05T10:41:45Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![nadaesposible](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.flowable.org/nadaesposible/32/3170_2.png) [@nadaesposible](https://forum.flowable.org/u/nadaesposible)\
**Post date:** [June 5, 2026, 10:41am UTC](https://forum.flowable.org/t/best-practice-for-filtering-kafka-messages-before-process-instance-creation/12579/1 "2026-06-05T10:41:45Z")

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Hi everyone:

Flowable version: 7.2

We have several BPMN processes triggered by a shared Kafka topic. Each process uses a dedicated channel with its own consumer group, but only a small subset of messages is relevant to each process — determined by a combination of Kafka headers and payload fields. Previously we handled this with an exclusive gateway after the start event, but this creates a process instance  
for every message only to discard most of them — generating a large number of short-lived history records at high volumes.

We want to move the check upstream so Flowable never creates an instance for non-matching messages. We’ve identified two interception points:

**Option 1 — InboundEventKeyDetector**

Inspect headers and payload and return the event definition key only when conditions are met, otherwise return “”, which will be eventually discarded by an existing InboundEventFilter.

**Option 2 — InboundEventFilter via eventFilterDelegateExpression**

Inspect headers and payload in an InboundEventFilter and return false for non-matching messages, keeping fixedValue for key detection.

* * *

Is there a recommended pattern for this use case? Is one of these preferable, or is there a third approach we haven’t considered?

Thanks!  
Pedro.

PS: We are about to upgrade to Flowable 8, in case there is another option there.

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**Author:** ![filiphr](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.flowable.org/filiphr/32/315_2.png) [@filiphr](https://forum.flowable.org/u/filiphr)\
**Post date:** [June 8, 2026, 8:47am UTC](https://forum.flowable.org/t/best-practice-for-filtering-kafka-messages-before-process-instance-creation/12579/2 "2026-06-08T08:47:54Z")

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Hey @nadaesposible,

The second option “ **InboundEventFilter via eventFilterDelegateExpression** ” would be the approach we would recommend to you. This was added for exactly the use case you are asking about.

Cheers,  
Filip

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**Author:** ![nadaesposible](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.flowable.org/nadaesposible/32/3170_2.png) [@nadaesposible](https://forum.flowable.org/u/nadaesposible)\
**Post date:** [June 8, 2026, 9:37am UTC](https://forum.flowable.org/t/best-practice-for-filtering-kafka-messages-before-process-instance-creation/12579/3 "2026-06-08T09:37:00Z")

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Good morning, Filip,

Thank you so much for the quick response and the clear answer. I really appreciate it.

Cheers,  
Pedro.