How to send a cloud to device message using Event Grid MQTT Broker?

I need to publish a message to a MQTT topic which my device has subscribed to from an application using the Event Grid MQTT Broker. Is this even possible or should I create a special MQTT client for publishing?

I couldn't find any documentation for cloud to device communication. I tried to create an EventGrid Topic for publishing but I did't manage to route the message to the EventGrid MQTT Broker so my device could receive it.

Yes, it is possible to send a cloud-to-device message using the Event Grid MQTT Broker, but it requires proper configuration of MQTT topics and permissions. Here's a general approach:

• Ensure your Event Grid namespace has the MQTT broker feature enabled.

• Create topic spaces for cloud-to-device communication. For example:

  • devices/{deviceId}/desired for publishing messages to specific devices.
  • devices/{deviceId}/reported for receiving responses from devices.

• Define permission bindings to allow your cloud application to publish messages to the desired topic and subscribe to the reported topic.

• Ensure devices have permissions to subscribe to the desired topic and publish to the reported topic.

• Use an MQTT client in your application to publish messages to the desired topic. The device subscribed to this topic will receive the message.

• You can find detailed guidance on implementing MQTT request-response messaging patterns with Event Grid here. This includes examples of topic configuration and permission bindings.

Refer this doc for Publishing and subscribing to MQTT messages on Event Grid Namespace