RE: Multiple Alt-Svc parameters of the same type

[Mike Bishop <[e-mail]>]

Certainly open to suggestions on how to simplify.  The "complex" encoding simply allows for things which can be represented in four characters instead of eight to do so.  It just feels a little unwieldy to make things like Q034 render as "51303334".

However, looking at it again, I note that while the *text* says no percent-encoding, the commend in the ABNF still says it's there.  Fixed that.

-----Original Message-----
From: Martin Thomson [mailto:[e-mail]] 
Sent: Monday, January 16, 2017 3:00 PM
To: Lucas Pardue <[e-mail]>
Cc: HTTP Working Group <[e-mail]>
Subject: Re: Multiple Alt-Svc parameters of the same type

I didn't mention this earlier, but I was wondering if it would be easier all around if we just renamed this from "v" to "quic" and made the semantics clearer.

I don't much like Mike's proposal with its multiple variant encodings either.  I proposed a simple numeric value (I chose hex, but decimal works fine), which is adequate.  I was concerned about the complexity of the encoding, but now we have two encodings, one of which is complex.

As far as multiple parameters go, it doesn't matter what the generic rules are as long as the specific ones are correct.

On 17 January 2017 at 05:48, Lucas Pardue <[e-mail]> wrote:
> Hello all,
>
> The “v” Alt-Svc parameter has seen some use in the wild, namely Google services offering the “quic” alternative service. To date this parameter was not defined anywhere but took the form of a comma-separated list of numbers e.g.
>
> Alt-Svc: quic=":443”; v="35,34"
>
> Mike Bishop is giving an official definition of the Alt-Svc “v” parameter, as part of https://tools.ietf.org/html/draft-ietf-quic-http-01#section-2.1, which is different than Google’s previous usage.
>
>> When multiple versions are supported, the "v" parameter MAY be 
>> repeated multiple times in a single Alt-Svc entry.  For example, if a 
>> server supported both version "Q034" and version 0x00000001, it would 
>> specify the following header:
>
>> Alt-Svc: hq=":443";v="x1";v="cQ034"
>
>> Where multiple versions are listed, the order of the values reflects 
>> the server's preference (with the first value being the most 
>> preferred version).
>
> This got me thinking, RFC 7838 doesn’t seem to give any direction on the handling of multiple parameters of the same type. For example, is it OK for a server to generate multiple “persist” parameters perhaps with different values, how should a client deal with that? Perhaps I’m worrying too much.
>
> I wondered if the Alt-Svc parameter IANA registry could use some new columns to define the allowed multiplicity of each parameter, and an indication of how to treat the ordering. Any thoughts?
>
> Regards
> Lucas
>
>
>
>
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