Subject: Re: Straw-man for our next charter

From: Larry Masinter <[email-masked]>
Date: Sun, 29 Jul 2012 10:57:25 -0700

what are the use cases and requirements for such gateways?

A general purpose omni-site 2.0->1.1 gateway might need to do sniffing of sites not known to have correct content-type headers, but 1.1->2.0 gateways shouldn't need to change content-type .... sniffing leaves correctly labeled content intact, of course. :)

Connected by DROID on Verizon Wireless

-----Original message-----
From: Adam Barth <[email-masked]>
To: Larry Masinter <[email-masked]>
Cc: "[email-masked]" <[email-masked]>
Sent: Sun, Jul 29, 2012 00:53:44 GMT+00:00
Subject: Re: Straw-man for our next charter

From the charter:

---8<---
Changes to the existing semantics of HTTP are out of scope in order to
preserve the meaning of messages that might cross a 1.1 --> 2.0 --> 1.1
request chain.
--->8---

http://datatracker.ietf.org/wg/httpbis/charter/

Changing how user agents interpret the Content-Type header would change the semantics of HTTP and are therefore out of scope for HTTP/2.0 according to our current charter.

Adam

On Sat, Jul 28, 2012 at 8:01 AM, Larry Masinter <[email-masked]<mailto:[email-masked]>> wrote:
The sniffing I was in particular hoping to stop is content-type sniffing.
http://tools.ietf.org/html/draft-ietf-websec-mime-sniff-03

" Many web servers supply incorrect Content-Type header fields with
   their HTTP responses.  In order to be compatible with these servers,
   user agents consider the content of HTTP responses as well as the
   Content-Type header fields when determining the effective media type
   of the response."

If browsers suddenly stopped sniffing HTTP/1.1 content, it would break existing web sites, so of course the browser makers are reluctant to do that.

However, if it was a requirement to supply a _correct_ content-type header for HTTP/2.0, and no HTTP/2.0 client sniffed, then sites upgrading to HTTP/2.0 would fix their content-type sending (because when they were deploying HTTP/2.0 they would have to in order to get any browser to work with them.)

Basically, sniffing is a wart which backward compatibility keeps in place. Introducing a new version is a unique opportunity to remove it.

The improved performance would come from having to look at the content to determine before routing to the appropriate processor.

Larry

-----Original Message-----
From: Amos Jeffries [mailto:[email-masked]<mailto:[email-masked]>]
Sent: Friday, July 27, 2012 11:53 PM
To: [email-masked]<mailto:[email-masked]>
Subject: Re: Straw-man for our next charter

On 28/07/2012 6:39 p.m., Larry Masinter wrote:
> re changes to semantics: consider the possibility of eliminating
> "sniffing" in HTTP/2.0. If sniffing is justified for compatibility
> with deployed servers, could we eliminate sniffing for 2.0 sites?
>
> It would improve reliability, security, and even performance. Yes,
> popular browsers would have to agree not to sniff sites running 2.0,
> so that sites wanting 2:0 benefits will fix their configuration.
>
> Likely there are many other warts that can be removed if there is a
> version upgrade.

Which of the several meanings of "sniffing" are you talking about exactly?

AYJ