Hi Romil,
You cannot create an API definition with a Kafka listener endpoint, as far as I know. As a workaround, you could create a front-end DataPower service, with a Kafka handler.
That service (e.g. MPGW) could pick up the messages, and relay them to the API Gateway. There are some considerations with chaining services (especially with virtual DataPower, and high volumes), but it is probably the easiest way to handle Kafka messages on the request side.
BTW, here is a presentation by IBM on DataPower V10 and Kafka:
https://community.ibm.com/community/user/middleware/viewdocument/datapower-v10-and-kafka?CommunityKey=b382f2ab-42f1-4932-aa8b-8786ca722d55------------------------------
Johan Thole
IT Specialist
IBM Cloud Nederland BV
Utrecht
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