[OASIS Issue Tracker] (MQTT-260) Add a CONNACK code of 'Try Another Server'

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

    [ https://issues.oasis-open.org/browse/MQTT-260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=63766#comment-63766 ] 

Jonathan Levell commented on MQTT-260:
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In short, I agree with the previoius comment (Ken's).

If we want to add a timer (which I suggest we don't do yet) we can add a separate timer metadata field.

The client library can notify the client application about the redirection string (and the return code and any other optional field we provide and the application can then choose in the future whether to go back to the original server) but after the notification, the library has enough information to connect and do the right thing.

> Add a CONNACK code of 'Try Another Server'
> ------------------------------------------
>
>                 Key: MQTT-260
>                 URL: https://issues.oasis-open.org/browse/MQTT-260
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 5
>            Reporter: Raphael Cohn
>            Assignee: Raphael Cohn
>            Priority: Critical
>
> If we add a CONNACK return code of 'Try Another Server', this makes it easier for over-loaded servers to tell clients to redirect. This works in conjunction with MQTT-259, which advocates the use of DNS SRV records.
> Indeed, if we also added server-originated DISCONNECT packets with this return code, we could get clients to cleanly migrate to another server when a server is shutdown for maintenance.
> Please note, I do not favour the server also reporting which new server to connect to. There in lies the route to madness, as it means the current server has to know the state of all the others. That's intimate knowledge.



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