Subscribe with QoS not working

[a1lu]

Hi, I tried to subscribe a topic with QoS > 0 and publish something into this topic. The result is, The QoS of the received message is only dependent on the QoS of the publisher. AFAIK the QoS level of subscriber and publisher are two different things, like this:

PUBLISHER -> qos_pub -> BROKER -> qos_sub -> SUBSCRIBER

I used the GatewayTester (run testscript including step 1) to make some logs. Test 1:

• subscribePredefTopic1() subscribes with QoS1
  • publishTopic1 publishes with QoS0 test1_gatewaytester.txt qos0_gateway.txt

Test 2:

• subscribePredefTopic1() subscribes with QoS1
  • publishTopic1 publishes with QoS1 test2_gatewaytester.txt qos1_gateway.txt

I would expect a PUBACK from the receiver like in Test2 also in Test1.

Best regards

[ty4tw]

Hi a1lu, You can't expect PUBACK.
It's a spec of MQTT.

According to the specification [MQTT-3.8.4-6],

The Server might grant a lower maximum QoS than the subscriber requested. The QoS of Payload Messages sent in response to a Subscription MUST be the minimum of the QoS of the originally published message and the maximum QoS granted by the Server.

[a1lu]

Ah, too bad. Thanks anyway.