[OASIS Issue Tracker] (MQTT-320) Expectations of timing accuracy in MQTT implementations

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    [ https://issues.oasis-open.org/browse/MQTT-320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=64163#comment-64163 ] 

Ian Craggs commented on MQTT-320:
---------------------------------

I would add that "because of the limitations of timing accuracy, the shorter the timeout value the more likely that any time error will be a sizeable proportion of that value."  Ken also suggested that any error would be late, but premature timeouts could not occur.  

> Expectations of timing accuracy in MQTT implementations
> -------------------------------------------------------
>
>                 Key: MQTT-320
>                 URL: https://issues.oasis-open.org/browse/MQTT-320
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 5
>            Reporter: Ian Craggs
>            Priority: Minor
>
> There are a number of aspects of MQTT which involve timings, starting with the keepalive interval, and some new features introduced in MQTT 5 such as message expiration.
> These timers are denoted in seconds (I don't think we have any exceptions to that), but the implementation of those timers in both servers and clients may not actually be at the resolution of small numbers of seconds.  I suggest that we include some wording to limit the expectation of accuracy when a small number of seconds is used on such a timer, where "small" is to be defined, but could be less than 10 for instance.



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