[OASIS Issue Tracker] (MQTT-538) Clarify SessionExpiry value for MQTT 5.0 equivalence of CleanSession to 0

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

    [ https://issues.oasis-open.org/browse/MQTT-538?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=76448#comment-76448 ] 

Richard Coppen commented on MQTT-538:
-------------------------------------

Reviewed with [~Andrew_Banks]Âand we believe this to be an error in the non-normative comment.Â

CleanStart=0 and SessionExpiry=0xFFFFFFFF (UINT_MAX) for MQTT 5.0 would provide the same as CleanSession=0 for 3.1.1.

However, since SessionExpiry doesn't exist in 3.1.1, the equivalent of CleanSession=1 requires a more detailed comparison as SessionExpiry doesn't exist in 3.1.1.

Â

This looks like an errata candidate. ThanksÂTakatoshi for spotting this.Â

> Clarify SessionExpiry value for MQTT 5.0 equivalence of CleanSession to 0
> -------------------------------------------------------------------------
>
>                 Key: MQTT-538
>                 URL: https://issues.oasis-open.org/browse/MQTT-538
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 5
>         Environment: Implementers of MQTT 5.0 and those migrating from 3.1.1
>            Reporter: Richard Coppen
>            Priority: Major
>              Labels: Usability, editorial
>
> Email to comments list fromÂTakatoshi Kondo:
> Â
> Hi,
>  
>  I have a comment about the following part of MQTT Version 5.0 document:
>  
>  https://urldefense.proofpoint.com/v2/url?u=https-3A__docs.oasis-2Dopen.org_mqtt_mqtt_v5.0_os_mqtt-2Dv5.0-2Dos.html-23-5FToc3901048&d=DwIFaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=HFOYf-FWdPMlPq2g5pc8M7HUYiSp2sC9P2hDoZdjdRo&m=cA-Wf0Sm4lOyst4wG_JZAokBhagLMEshsXwWx1SZCa4&s=4QRoSC7d0BF5IMtW5-G3y_ZW9ZyAbSTS74i_dfysi_k&e= 
>  
>  > 3.1.2.11.2 Session Expiry Interval
>  >
>  > ...snip...
>  >
>  > Non-normative comment
>  >
>  > Setting Clean Start to 1 and a Session Expiry Interval of 0, is equivalent to setting CleanSession to 1 in the MQTT Specification Version 3.1.1. Setting Clean Start to 0 and no Session Expiry Interval, is equivalent to setting CleanSession to 0 in the MQTT Specification Version 3.1.1.
>  
>  I thin that "Setting Clean Start to 0 and no Session Expiry Interval,
>  is equivalent to setting CleanSession to 0 in the MQTT Specification
>  Version 3.1.1." is not correct.
>  
>  Because "no Session Expiry Interval" is equivalent to set to 0.
>  
>  The spec said that as follows:
>  
>  > If the Session Expiry Interval is absent the value 0 is used. If it is set to 0, or is absent, the Session ends when the Network Connection is closed.
>  >
>  > If the Session Expiry Interval is 0xFFFFFFFF (UINT_MAX), the Session does not expire.
>  
>  So I think that the sentence
>  
>  "Setting Clean Start to 0 and no Session Expiry Interval, is
>  equivalent to setting CleanSession to 0 in the MQTT Specification
>  Version 3.1.1."
>  
>  should be something like as follows:
>  
>  "Setting Clean Start to 0 and a Session Expiry Interval of
>  0xFFFFFFFF(UINT_MAX), is equivalent to setting CleanSession to 0 in
>  the MQTT Specification Version 3.1.1."
>  
>  Am I missing something?
>  
>  Thanks,
>  Takatoshi



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