Can MQTT v3 client work with MQTT v5 server?

Question

I wanted to make use of Shared Subscription feature of MQTT v5. But currently I am using AKKA MQTT client which doesn't support MQTT v5 client. Can I still use v3 MQTT paho client and use Shared Subscription feature?

Answer 1

That should not be a problem as from the viewpoint of an MQTT v3 client a shared subscription is just like any subscription.

The broker has to do all the work regarding shared subscription logic.

The only hindrances I can see are:

• that an MQTT broker might support v5 but not v3/v3.1.1
• the broker doesn't support shared subscriptions in general (yes they exist)
• the broker supports all MQTT versions but handles them as two different protocols (not sure if this is a thing)