[OASIS Issue Tracker] (MQTT-494) Unsubscribe actions does not define shared sub actions

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     [ https://issues.oasis-open.org/browse/MQTT-494?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ken Borgendale updated MQTT-494:
--------------------------------

    Assignee: Ken Borgendale
    Proposal: 
Add the following paragraph to section 3.10.4 UNSUBSCRIBE Actions:

If a Topic Filter represents a Shared Subscription, this Session is detached from the Shared Subscription.  If this Session was the only Session that the Shared Subscription was associated with, the Shared Subscription is deleted.  Refer to section 4.8.2 for a description of Shared Subscription handling.

Add the reasson code 0x12 (Other shares exist) which indicates that although this shared subscription was detached from this session, it is still attached to other sessions and thus is not fully deleted.  We should say that in cases where the server is not sure the 0x00 (Success) reason code should be used.

Adding some test in section 3.10.4 UNSUBSCRIBE Actions is a simple change and presumable not at all controversial.

We need to discuss whether we should add the reason code to indicate that this UNSUBSCRIBE did not cause the shared subscription to be deleted.  Note that this does not therefore imply that by the time the client sees this return code it is still true and this is only a transient state.

> Unsubscribe actions does not define shared sub actions
> ------------------------------------------------------
>
>                 Key: MQTT-494
>                 URL: https://issues.oasis-open.org/browse/MQTT-494
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 5, CSD01
>            Reporter: Ken Borgendale
>            Assignee: Ken Borgendale
>             Fix For: 5
>
>
> Section 3.10.4 (UNSUBSCRIBE Actions) does not define the actions to take when the subscription is a shared sub.
> At the very least this needs a reference to section 4.8.2 (Shared Subscriptions) but should have some text here.
> The 0x00 (Success) return code for UNSUBACK needs to be clarified.  Saying the subscription is deleted is at best ambiguous in the case of a shared subscription.
> There should be another return code to indicate whether the subscription still exists given that this session is no longer attached to the shared subscription.  That is, was this the last session attached to the shared sub.



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