[Question] how to publish with MQTT QOS 1/2

[dakhnod]

Is there a way to publish a message via NATS, so that it gets delivered to MQTT clients with QOS 1 or 2?

From the documentation, we didn't find a way of controlling the MQTT QOS when publishing over NATS, only when publishing via MQTT.

Currently, to achieve QOS 1, we publish to $MQTT.msgs.${subject} while setting the Nmqtt-Pub header.

Is there a sleaker alternative?

[kozlovic]

@dakhnod Currently no. If we wanted to support QoS1/2 from NATS publishers, then the server would have to look for some headers in every incoming NATS message. I believe that would cause a performance impact to all users, which is not ideal.

[dakhnod]

Understood, thanks! Is our current approach viable?

[kozlovic]

Unless we decide to add a feature in the server to do that automatically, and if you really need NATS core publisher to publish as if an MQTT message was sent from an MQTT publisher with QoS1/2, then that is the only approach you have, but understand that this is "not supported", meaning you are sending directly to the MQTT message stream, possibly bypassing some code. Note that for QoS2 the header "Nmqtt-Subject" needs also to be set.

[dakhnod]

Thanks!