UNSUBALL : Cancel all subscriptions.

[ನಾಗೇಶ್ ಸುಬ್ರಹ್ಮಣ್ಯ (Nagesh S)]

Hi,

Suppose, the MQTT protocol has another command - UNSUBALL. When the broker receives this command, it interprets it as multiple UNSUBSCRIBE command for every topic the given client has subscribed to. And, so in response, the broker sends those many UNSUBACK responses. Or, perhaps, one UNSUBALL with reason codes as 0 (all un-subscribed), 1 (total failure), 2 (partially un-subscribed) and topic strings that were unsubscribed.

When developing a MQTT client, one can maintain a local store of the topics subscribed and then issue UNSUBSCRIBE to all these in a loop. However, with this command the overhead of maintaining such a store would be removed.

Thoughts, opinions on this "lazy weekend" idea ?

Regards,

Nagesh

[Ian Craggs]

When we implemented MQTT servers in IBM in the 2000s, we used to treat "unsubscribe #" as special, to do as you describe and delete all subscriptions (only one unsuback was returned).  This was at the suggestion of Andy Stanford-Clark, as far as I remember.  However, some of the people working on the MQTT 3.1.1 standardization didn't like this option, so it wasn't included.   You can achieve something similar of course, by connecting non-cleansession.

Ian

[Rahul Gupta]

Some of the discussion details are available in this JIRA.

https://issues.oasis-open.org/browse/MQTT-64

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[ನಾಗೇಶ್ ಸುಬ್ರಹ್ಮಣ್ಯ (Nagesh S)]

# is a broker wide wild card. Whereas I was thinking client wide 'wild card'.

A UNSUBALL allows an easy way for 'factory reset'.

Sent from phone. Pardon brevity and lingiuistic mistakes.

[Paul Fremantle]

Nagesh

This would be worth putting to the working group for the next phase of spec'ing. However, as described above, a disconnect followed by a reconnect with clean session= true will achieve the same. Since you are aiming to stop getting all notifications, I think it is reasonable that you would momentarily disconnect.

Paul

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