[OASIS Issue Tracker] Commented: (MQTT-71) Are messages order within Topic+Qos or within Qos

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

    [ http://tools.oasis-open.org/issues/browse/MQTT-71?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=34351#action_34351 ] 

Nick O'Leary commented on MQTT-71:
----------------------------------

I've been thinking about this some more in terms of what is actually useful for applications and not being too onerous on implementations.

Whilst topic has never factored into it for me before, I can see merit in defining the minimum requirement for ordering to be "within QoS on a topic". Otherwise, a server cannot have multiple worker threads handle the workload from a single client without some meaty synchronisation.

A server may choose to offer a broader guarantee of ordering within QoS across all topics; such an implementation would likely have to be single-threaded per client connection to ensure this.

So, I think we should state that, as a minimum, a server should guarantee ordering of messages with the same QoS and Topic Name.
We should consider also describing, non-normatively, how ordering within QoS across all Topics can be achieved.

> Are messages order within Topic+Qos or within Qos
> -------------------------------------------------
>
>                 Key: MQTT-71
>                 URL: http://tools.oasis-open.org/issues/browse/MQTT-71
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Improvement
>          Components: core
>            Reporter: Andrew Banks
>
> The input specification states 
> •	With an in-flight window greater than 1, message ordering can only be achieved within the QoS level.
> Should we state that 
> messages with the same Qos and Topic Name are delivered in order
> or
> messages with the same Qos regardless of Topic Name are delivered in order

-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: http://tools.oasis-open.org/issues/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira