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Re: FYI... Binary Optimized Header Encoding for SPDY

From: Mike Belshe <mike@belshe.com>
Date: Fri, 3 Aug 2012 10:15:00 -0700
Message-ID: <CABaLYCtjo2=L5YGSGVTv_4CpEbdrkLByM-HnSmBgyWJt835UWA@mail.gmail.com>
To: James M Snell <jasnell@gmail.com>
Cc: Jonathan Ballard <dzonatas@gmail.com>, Martin J. Dürst <duerst@it.aoyama.ac.jp>, Poul-Henning Kamp <phk@phk.freebsd.dk>, "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
OK.  More concrete use cases for why we need this would help me understand
better.

>From the User Agent's perspective - how would it know whether a given
HTTP/2 server would be able to grok its UTF8 headers?  Just try and fail?

If you send a UTF8 header, and the origin server can't handle it, does it
cause a failure of the entire request?  Or is this a partial failure?  I
see you classified some as ignorable and others not.  Is the error code
specifically a "couldn't pass UTF8 header" error?  If not, how would the UA
differentiate an error that the server didn't grok the UTF8 vs other server
errors?

These are the new edge cases I was referring to earlier.

Mike


On Fri, Aug 3, 2012 at 8:52 AM, James M Snell <jasnell@gmail.com> wrote:

> I'll say it again: simply allowing header values to contain UTF-8
> characters does not break compatibility with 1.1 because the existing
> header definitions for the existing headers would not be changed. The
> change would impact new header definitions or applications that are
> specifically targeted for 2.0 implementations.
>
> For example, suppose we define a new binary optimized encoding for the
> host header that accepts IDN's. That new encoding does not change the
> details of the existing Host header in HTTP/1.1. When an intermediary
> translates the 2.0 message into a 1.1 message, it would convert the IDN
> into a proper punycode value within the 1.1 Host header. If the
> intermediary happens across some other arbitrary new header using UTF-8
> that it does not understand or know how to translate, it can either ignore
> it or return a protocol error. Interoperability is not affected at all.
>
> Limits are a bad thing... aren't they? ;-)
>
> - James
>
> On Fri, Aug 3, 2012 at 8:33 AM, Mike Belshe <mike@belshe.com> wrote:
>
>> One of the charter requirements of HTTP/2, I thought, was interop to
>> HTTP/1.1 servers.
>>
>> If so, how would we pass UTF8 headers to HTTP/1.1 servers?
>>
>> If we can't then we don't need to support them, right?
>>
>> Mike
>>
>>
>> On Fri, Aug 3, 2012 at 8:30 AM, Jonathan Ballard <dzonatas@gmail.com>wrote:
>>
>>> ASCII is not "trivially UTF8." UTF8 lacks the available flow control of
>>> ASCII. Any conversion between ASCII and EBCDIC is best done in hardware. We
>>> already know the security issue of conversions from unicode to EBCDIC, and
>>> I doubt that is something we can scheme here on on-topic.
>>>
>>>
>>> On Friday, August 3, 2012, "Martin J. Dürst" wrote:
>>>
>>>> On 2012/08/02 17:27, Poul-Henning Kamp wrote:
>>>>
>>>>> In message<
>>>>> CABaLYCv7U7iLBu5+8Nb9Wa1VeQguoMLJw4VOCbDBQK3WoE-sFg@mail.gmail.com>
>>>>> , Mike Belshe writes:
>>>>>
>>>>>  * I don't think we need utf-8 encoded headers.  Not sure how you'd
>>>>>>>> pass
>>>>>>>>
>>>>>>> them off to HTTP anyway?
>>>>>>>
>>>>>>
>>>>>> I just don't see any problem being solved by adding this?  If there
>>>>>> is no
>>>>>> benefit, we should not do it, right?
>>>>>>
>>>>>
>>>>> If this would solve any major problems inside a 20 year horizon, we
>>>>> should do it.
>>>>>
>>>>
>>>> It will solve quite a few problems, some of them major, maybe not for
>>>> HTTP itself, but for the applications on top. It will actually solve some
>>>> problems that have been around for at least the last 15 years.
>>>>
>>>> HTML and HTTP were created when the breakthrough of iso-8859-1
>>>> (Latin-1) in Western Europe was predictable (the nascent Web helped to
>>>> unify the Western Europe 'national' 7-bit and 8-bit encodings quite a bit).
>>>>
>>>> At least as early as 1995 (RFC 2070) or 1996 (RFC 2130, RFC 2277), it
>>>> was clear to those concerned that Unicode and UTF-8 was the way of the
>>>> future. As everybody should be able to confirm when thinking about
>>>> US-ASCII, using a single character encoding (rather than e.g. ASCII and
>>>> EBCDIC or some such alternatively) brings HUGE benefits. The same is true
>>>> when streamlining from a zoo of character encodings to UTF-8.
>>>>
>>>> These days, over 60% of the Web is already in UTF-8, and if you add in
>>>> the 20% of pure ASCII which is trivially also UTF-8, it's 80%. All other
>>>> encodings are in serious decline. (see p. 52 of the July IEEE Spectrum).
>>>> And efforts such as HTML5 are strongly pushing to get more UTF-8. I think
>>>> lots of HTTP users would appreciate a better commitment from HTTP with
>>>> respect to character encoding in headers and the like. What's currently
>>>> there is really just a mess, and should be cleaned up.
>>>>
>>>>
>>>> Regards,    Martin.
>>>>
>>>>
>>
>
Received on Friday, 3 August 2012 17:15:28 GMT

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