How to send Event Grid subscriber logic app Response to event grid custom topic Azure

Question

I am having Event grid publisher logic app based on service bus, subscriber logic app and having Event Grid custom Topic

Whenever I am publishing the event ,every time I am getting 200 OK response. I want to have a retry mechanism where I should only complete the service bus message on successful processing by the subscriber and event grid should know the response of subscriber response.

This is the response I am getting back

had added the validationCode in the data payload event grid publish

Sending response from subscriber and this is my event filter in topic subscription

How can in my logic app i can send the response back to the event grid publisher logic app ?

Answer 1

Event Grid does not support a request/response kind of scenario. You would have to employ an intermediary service to handle the response like sending the response into a different service bus queue.

You could leverage message deferral in this scenario where in the first logic app would defer the message while passing the sequence number of the message in the Event Grid message.

The second logic app would process the event and push a message into the response queue with the sequence number of the message it processed along with success/failure message.

A third logic app that triggers from messages in the response queue would fetch the message using the sequence number and complete it then if successful. If the response message indicates a failure, you could either dead letter the original message or re-queue it based on your scenario.

Another approach could be to simply call the second logic app directly, unless Event Grid is required for some other reason apart from decoupling.