Re: [Webpush] Alexey Melnikov's Discuss on draft-ietf-webpush-protocol-11: (with DISCUSS and COMMENT)

[Martin Thomson <[e-mail]>]

Hi Alexey,

Thanks for going through this so thoroughly.

Most of these are - as you say - trivial, and I have PRs for the
issues that you identified, see below.

On 13 October 2016 at 01:39, Alexey Melnikov <[e-mail]> wrote:
> 1) In 5.2: is there upper limit on the TTL? The ABNF doesn't restrict the
> value, but it is important for interoperability

Magnus Westerlund noted the same problem, so we've cribbed some text
from other HTTP documents.  You can see the updated text here:
https://github.com/webpush-wg/webpush-protocol/pull/131

> 2) In 5.3: urgency is defined as a list of one or more values. The
> description says that it defines the lowest value allowed. There is also
> a sentence prohibiting multiple values. Why is this a set and how would
> multiple values be interpreted?

This was in keeping with providing a definition for the header field
that is consistent with other HTTP header fields, but I believe that
you are correct in that the list construction in the ABNF is a hazard
rather than a feature:
https://github.com/webpush-wg/webpush-protocol/pull/135

> 3) In 6:
>
> I don't know where the ":link" Pseudo-Header field came from. Can you
> clarify where it is defined?

Pure editorial error, it's a real header field, as in RFC 5988:
https://github.com/webpush-wg/webpush-protocol/pull/134

> 1)
> I see you defined a new HTTP Header Field "Urgency". Can you reuse email
> header field "Priority" instead (possibly extending it)
>       Can be 'normal', 'urgent', or 'non-urgent' and can influence
>       transmission speed and delivery.
> ?

The working group discussed this specifically and at some length.
Priority was actually one of my original proposals.  The concern is
that this is NOT a priority, but an urgency.  That the values are the
same is merely convenient.

> 2) In 4.1:
>
> Can 429 be used when no subscription set is specified? (If yes, this
> should be mentioned in section 4)

I think that I'd rather leave this to Section 4.1.  It follows the
text immediately. subsection of 4 anyway.

> 3) In 6.1: ":link" is included in the PUSH_PROMISE and not the HEADERS
> block (when compared to section 6). Is this intentional or should one of
> the examples be fixed?

Yes, the link relation should be in the response, not the promise.  Thanks.

> 4) In general case it is not possible to achieve message reliability
> because a push server is allowed to expire messages after they were
> accepted for delivery due to overload. (Similarly for forced subscription
> expiration.) I don't think the document makes this clear in Section 7.4.

You are right, we mention this elsewhere, but not here:
https://github.com/webpush-wg/webpush-protocol/pull/136

> 5) In 9.3:

Alissa covered this already.