Re: I-D Action: draft-ietf-httpbis-header-structure-01.txt

On 26/04/17 11:16, Matthew Kerwin wrote:
>
>
> On 26 April 2017 at 07:43, Poul-Henning Kamp <phk@phk.freebsd.dk 
> <mailto:phk@phk.freebsd.dk>> wrote:
>
>     --------
>     In message <99c23bc4-069e-fd33-5b48-0942e0708d31@treenet.co.nz
>     <mailto:99c23bc4-069e-fd33-5b48-0942e0708d31@treenet.co.nz>>, Amos
>     Jeffries
>     writes:
>
>     >Reading section 7.1 I am wondering if this is significant enough
>     to use
>     >HTTP/1.2 version number for 1.x agents as the signal that the
>     sender can
>     >receive any header in self-describing Common Structure.
>
>     That's an interesting question...
>
>
> ​Very interesting.  The request line is a hop-by-hop message, right?  
> So it couldn't be used as a signal for end-to-end headers.

I'm thinking that headers affected by this signal would have a 'legacy' 
format - for example Date. So this use-case would be hop-by-hop 
opportunistic performance optimization. Any agent using it would need to 
be able to map.

> How many middleboxen out there are likely to inspect the request line 
> only as far as 'HTTP_VERSION > 1.0' and then barf if one of their 
> response headers looks weird?  Although I suppose the answer is not 
> that different from: how many will forward X-Accept-Fancy-Headers 
> blindly and then barf... Pity there was no strong hop-by-hop vs 
> end-to-end flag on headers.
>
> Cheers
> -- 
>   Matthew Kerwin
> http://matthew.kerwin.net.au/