Re: [Webpush] AD evaluation: draft-ietf-webpush-protocol-09

[Martin Thomson <[e-mail]>]

Thanks for reviewing Alissa,

The other comments look like they have mechanical fixes.  We will get to that.

On 22 September 2016 at 13:25, Alissa Cooper <[e-mail]> wrote:
> = Section 5.4 =
>
> "Delivery receipts for the deleted message
>    SHOULD be suppressed."
>
> Why is this a SHOULD rather than a MUST? It seems incorrect in all cases to send a delivery receipt for a message that never gets delivered.

I realize that this is actually too short to be comprehensible.  What
I think that this was trying to capture was that sometimes replaced
messages might be delivered successfully, but the acknowledgment might
be still in transit toward the server.  That acknowledgement could
trigger a delivery receipt.

This recommends that receipts be suppressed in this case.  They might
not be given the distributed nature of the push service.
(Acknowledgments might be handled in a stateless fashion, and checking
that a replacement has occurred can be expensive; preventing the race
adds cost and latency also.)

>>>
A push message replacement request creates a new push message resource
and simultaneously deletes any existing message resource that has a
matching topic. If an attempt was made to deliver the deleted push
message, an acknowledgment could arrive at the push service after the
push message has been replaced.  Delivery receipts for such deleted
messages SHOULD be suppressed.
<<<