Re: [mqtt-comment] Clarify Will Delay Interval can appear in the PUBLISH packet send by the broker

[Roger Light <roger@atchoo.org>]

Hi Takatoshi,

I also think that the purpose of Will Delay Interval is changing the

broker's behavior, and it is not so useful if the Will Delay Interval
is sent to the client.
I think that it is reasonable that if the broker removes Will Delay
Interval from the Will Properties but remains other Will Properties.
However, I couldn't find such a description.

You are correct that the broker should not be sending the Will Delay Interval property. The table in 2.2.2.2 Property that you link to is the description that you are looking for. It only allows the Will Delay Interval property to be used in the will properties, and hence must not be sent with the PUBLISH.

3.1.3.2 Will Properties states "The Will Properties field defines the Application Message properties to be sent with the Will Message when it is published, and properties which define when to publish the Will Message." Will Delay Interval comes under "properties which define when to publish".

So I do not believe there is any ambiguity in the spec, but agree with you that it would be helpful to have each of the properties in 3.1.3.2 explicitly stated as whether they should be sent with the published will or not.

Regards,

Roger