OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

mqtt message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]


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


    [ https://issues.oasis-open.org/browse/MQTT-260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=62855#comment-62855 ] 

Jonathan Levell commented on MQTT-260:
--------------------------------------

My worry about a return code with no URI is cleansession=false (in 3.1.1 speak) clients. The server has state for that client. Trying "another" server doesn't give the client any idea where the server-side state for that client is. Using DNS-SRV (or other DNS lookup not involving a clientid) doesn't tell the client where the server-side state for *that* client is.

The code means the state is not here - but (without a load-balancer/proxy or complicated logic in the client both of which I'd argue are more complicated that the optional URI) the client doesn't know where its server-side state is available (on the assumption that the state is not available to all the brokers in the distributed system).

> 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: futures
>    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.



--
This message was sent by Atlassian JIRA
(v6.2.2#6258)


[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]