# \[Event Registry\] Cannot start process from Kafka event

**URL:** <https://forum.flowable.org/t/event-registry-cannot-start-process-from-kafka-event/5505>\
**Category:** Flowable Engine\
**Created:** [February 24, 2020, 3:23am UTC](https://forum.flowable.org/t/event-registry-cannot-start-process-from-kafka-event/5505 "2020-02-24T03:23:23Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![tannth](https://avatars.discourse-cdn.com/v4/letter/t/b3f665/32.png) [@tannth](https://forum.flowable.org/u/tannth)\
**Post date:** [February 24, 2020, 3:23am UTC](https://forum.flowable.org/t/event-registry-cannot-start-process-from-kafka-event/5505/1 "2020-02-24T03:23:23Z")

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Hi everyone,

I’m trying to make a simple demo using spring boot + event registry + kafka, whenever a event comming the flowable engine will trigger create a process

This is my startEvent element

> ```
> <startEvent id="requestVideoConferenceEventTask"> <extensionElements>
> <flowable:eventType xmlns:flowable="http://flowable.org/bpmn"><![CDATA[requestVideoConferenceEvent]]></flowable:eventType>
> <flowable:eventName xmlns:flowable="http://flowable.org/bpmn"><![CDATA[Request Video Conference Event]]></flowable:eventName>
> <flowable:eventOutParameter xmlns:flowable="http://flowable.org/bpmn" source="correlationId" sourceType="string" target="correlationId"></flowable:eventOutParameter>
> <flowable:eventCorrelationParameter xmlns:flowable="http://flowable.org/bpmn" name="correlationId" type="string" value="${correlationId}"></flowable:eventCorrelationParameter>
> <flowable:channelKey xmlns:flowable="http://flowable.org/bpmn"><![CDATA[requestVideoConferenceChannel]]></flowable:channelKey>
> <flowable:channelName xmlns:flowable="http://flowable.org/bpmn"><![CDATA[Reques Video Conference Channel]]></flowable:channelName>
> <flowable:channelType xmlns:flowable="http://flowable.org/bpmn"><![CDATA[kafka]]></flowable:channelType>
> <flowable:channelDestination xmlns:flowable="http://flowable.org/bpmn"><![CDATA[REQUEST_VIDEO_CONFERENCE_TOPIC]]></flowable:channelDestination>
> <flowable:keyDetectionType xmlns:flowable="http://flowable.org/bpmn"><![CDATA[fixedValue]]></flowable:keyDetectionType>
> <flowable:keyDetectionValue xmlns:flowable="http://flowable.org/bpmn"><![CDATA[requestVideoConferenceEvent]]></flowable:keyDetectionValue>
> </extensionElements>
> </startEvent>
> 
> ```

In debugger, when I push a message to topic then the message event will go to KafkaChannelMessageListenerAdapter.java, but I don’t see any process is created

 ![image](https://canada1.discourse-cdn.com/flex035/uploads/flowable/original/2X/1/1f86545f9bcfe98177bc0b0585bf76237ddd194d.png)

Event file:

> {  
> “key”: “requestVideoConferenceEvent”,  
> “name”: “Request Video Conference Event”,  
> “inboundChannelKeys”: [  
> “requestVideoConferenceChannel”  
> ],  
> “correlationParameters”: [  
> {  
> “name”: “correlationId”,  
> “type”: “string”  
> }  
> ],  
> “payload”: [  
> {  
> “name”: “correlationId”,  
> “type”: “string”  
> }  
> ]  
> }

Channel file:

> {  
> “key”: “requestVideoConferenceChannel”,  
> “category”: “channel”,  
> “name”: “Request Video Conference Channel”,  
> “channelType”: “inbound”,  
> “type”: “kafka”,  
> “topics”: [“REQUEST\_VIDEO\_CONFERENCE\_TOPIC”],  
> “deserializerType”: “json”,  
> “channelEventKeyDetection”: {  
> “jsonField”: “eventKey”  
> }  
> }

Any help for that

Thanks.

---

<div class="post-metadata">

**Author:** ![tannth](https://avatars.discourse-cdn.com/v4/letter/t/b3f665/32.png) [@tannth](https://forum.flowable.org/u/tannth)\
**Post date:** [February 24, 2020, 8:10am UTC](https://forum.flowable.org/t/event-registry-cannot-start-process-from-kafka-event/5505/2 "2020-02-24T08:10:19Z")

</div>

Finally, I found the issue, because I start event with a correlation parameter, In **org.flowable.engine.impl.eventregistry.BpmnEventRegistryEventConsumer.eventReceived(EventInstance eventInstance)**, the engine will try to **findEventSubscriptions(ScopeTypes.BPMN, eventInstance, correlationKeys)** which stored at ACT\_RU\_EVENT\_SUBSCR with correlationKey = CONFIGURATION\_

Correct Config

> ```
> <startEvent id="requestVideoConferenceEventTask"><extensionElements>
> <flowable:eventType xmlns:flowable="http://flowable.org/bpmn"><![CDATA[requestVideoConferenceEvent]]></flowable:eventType>
> <flowable:eventName xmlns:flowable="http://flowable.org/bpmn"><![CDATA[Request Video Conference Event]]></flowable:eventName>
> <flowable:eventOutParameter xmlns:flowable="http://flowable.org/bpmn" source="correlationId" sourceType="string" target="correlationId"></flowable:eventOutParameter>
> <flowable:channelKey xmlns:flowable="http://flowable.org/bpmn"><![CDATA[requestVideoConferenceChannel]]></flowable:channelKey>
> <flowable:channelName xmlns:flowable="http://flowable.org/bpmn"><![CDATA[Reques Video Conference Channel]]></flowable:channelName>
> <flowable:channelType xmlns:flowable="http://flowable.org/bpmn"><![CDATA[kafka]]></flowable:channelType>
> <flowable:channelDestination xmlns:flowable="http://flowable.org/bpmn"><![CDATA[REQUEST_VIDEO_CONFERENCE_TOPIC]]></flowable:channelDestination>
> <flowable:keyDetectionType xmlns:flowable="http://flowable.org/bpmn"><![CDATA[fixedValue]]></flowable:keyDetectionType>
> <flowable:keyDetectionValue xmlns:flowable="http://flowable.org/bpmn"><![CDATA[requestVideoConferenceEvent]]></flowable:keyDetectionValue>
> </extensionElements>
> </startEvent>
> 
> ```

Event file:

> {  
> “key”: “requestVideoConferenceEvent”,  
> “name”: “Request Video Conference Event”,  
> “inboundChannelKeys”: [  
> “requestVideoConferenceChannel”  
> ],  
> “correlationParameters”: ,  
> “payload”: [  
> {  
> “name”: “correlationId”,  
> “type”: “string”  
> }  
> ]  
> }

---

<div class="post-metadata">

**Author:** ![nrus](https://avatars.discourse-cdn.com/v4/letter/n/a9adbd/32.png) [@nrus](https://forum.flowable.org/u/nrus)\
**Post date:** [October 14, 2020, 9:44am UTC](https://forum.flowable.org/t/event-registry-cannot-start-process-from-kafka-event/5505/3 "2020-10-14T09:44:51Z")

</div>

hi @tannth, i’m wondering why you had to define the KafkaChannelMessageListenerAdapter class. All the tutorials online don’t have this class.  
I have defined only the process+event+channel definitions, isn’t this enough to make your process start when an event is produced on kafka? With only these 3 definitions, i’m not able to start my process so i’m wondering if i’m missing something.

Thank you,  
Narcisa

---

<div class="post-metadata">

**Author:** ![tannth](https://avatars.discourse-cdn.com/v4/letter/t/b3f665/32.png) [@tannth](https://forum.flowable.org/u/tannth)\
**Post date:** [October 14, 2020, 1:13pm UTC](https://forum.flowable.org/t/event-registry-cannot-start-process-from-kafka-event/5505/4 "2020-10-14T13:13:24Z")

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> [@nrus](#):
>
> t able to st

Thanks for your response @nrus, KafkaChannelMessageListenerAdapter class is inside the engine, I don’t try to write it.

I can say, we only need defined process+event+channel then the engine will work fine (of couse if your config is correct)

Thanks.  
TanNTH