SUBACK failure response code

[Paolo Patierno]

Hi all,

what are the main reasons for a broker to reply with "failure" in SUBACK packet to a client ?

Thanks,

Paolo

[Roger Light]

Hi Paolo,

I'd say access denied, or topic not available. For the latter - some
brokers require topics to be preconfigured.

Cheers,

Roger

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[Paolo Patierno]

Hi Roger,
with "access denied" do you mean that a broker can avoid that a client (connected with a username/password) could subscribe to some topics ?
Regarding "topic not available" of course it is valid only for brokers that allow access only to preconfigured topics.
However, they are all things not well specified in the standard but are free of implementaion in the broker.

Paolo

[Roger Light]

Hi Paolo,

> with "access denied" do you mean that a broker can avoid that
> a client (connected with a username/password) could subscribe
> to some topics ?

Yes, exactly.

Regards,

Roger

[Jian Zhen]

Also if the topic is invalid? So if you subscribe to a topic of "a/b#" then the broker can respond "failure".