[OASIS Issue Tracker] (MQTT-498) No way to set properties on will message

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

    [ https://issues.oasis-open.org/browse/MQTT-498?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=67579#comment-67579 ] 

Ken Borgendale commented on MQTT-498:
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For the packet format invalid we should use 0x99 (Payload format invalid) rather than creating a new reason code which means the same thing.

We need to either add 0x94 (Topic Alias invalid) to CONNACK, or declare that a Topic Alias property is not allowed in a will message.  I would vote to disallow the topic alias but if we allow it we need some text about how it applies to the will message.

In the case of Publication Expiry Interval we should clarify when this interval starts.  I assume we mean the time from the CONNECT to when the will message is sent to not decrement the expiry interval, but this needs to be stated explicitly.

We must explicitly state that the Subscription Identifier property is not allowed in the will PUBLISH.  The current spec in section 3.3.4 says the client cannot send a Subscription ID to the server, but I would presume that all of section 3.3.4 (PUBLISH Actions) is outside of the specification of the format of the will PUBLISH within a CONNECT.

I would prefer not to allow Response Topic and Correlation Data properties on a will message, but if we do, we need some text about this or modify the existing text.

In general we must look thru all references in the spec to PUBLISH and understand if they apply to the will PUBLISH.  Many of these references talk about the PUBLISH packet, and this is not a PUBLISH packet but this is not a PUBLISH packet.  The text in section 3.3 (PUBLISH message) has a lot of discussion about forwarding a message.  We need to either duplication this text in a section about the will PUBLISH, or put text scattered thruout section 3.3 about the meaning of these items in a will PUBLISH.


> No way to set properties on will message
> ----------------------------------------
>
>                 Key: MQTT-498
>                 URL: https://issues.oasis-open.org/browse/MQTT-498
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 5, CSD01
>            Reporter: Ian Craggs
>
> There is no way to set properties on the will message. This may have been discussed but on implementation it seems like a significant omission and asymmetry. Content type and payload format, are two examples of properties which would be very useful. 
> The behaviour of properties on retained messages appears to be unspecified. It could be interpreted that properties are not stored nor propagated, but that seems unlikely to be desirable. In the event of propagation, the behaviour of some properties such as the publication expiry interval, should be clarified. I suggest that the "time of receipt" for a retained message should be the time of receipt of the subscribe request which triggers it.



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