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Re: h2#404 requiring gzip and/or deflate

From: Zhong Yu <zhong.j.yu@gmail.com>
Date: Tue, 25 Feb 2014 15:02:36 -0600
Message-ID: <CACuKZqEifruZ=x-s_ZesXyKjis99RejXy+nNeYY4qyRQ+WZ73w@mail.gmail.com>
To: Jesse Wilson <jesse@swank.ca>
Cc: Jeff Pinner <jpinner@twitter.com>, Mark Nottingham <mnot@mnot.net>, Roberto Peon <grmocg@gmail.com>, Patrick McManus <mcmanus@ducksong.com>, HTTP Working Group <ietf-http-wg@w3.org>, Martin Thomson <martin.thomson@gmail.com>
On Tue, Feb 25, 2014 at 8:32 AM, Jesse Wilson <jesse@swank.ca> wrote:
> In Billy Hoffman's blog[1], and elsewhere, there's discussion over the fact
> that 'deflate' is used to describe two different algorithms. And several
> browsers and webservers got it wrong.
>
> "So, DEFLATE, and Content-Encoding: deflate, actually means the response
> body is composed of the zlib format (zlib header, deflated data, and a
> checksum)."
>
> [1]: http://zoompf.com/blog/2012/02/lose-the-wait-http-compression
>
> If the spec is going to require that clients support deflate compression, it
> should use strong language to remind implementors that 'deflate' means zlib.

Or create a new name to remove the ambiguity of the old name.

("de-flate" always sounds weird to me:)  it sounds like it is undoing
an operation, while it is actually operating on the original data)

>
> And if 'deflate' is implicit, then middleboxes that bridge HTTP/2 clients
> to HTTP/1.1 servers will need to transcode/decompress deflated data for the
> legacy browsers[2] that misinterpret the spec.
>
> [2]: http://www.vervestudios.co/projects/compression-tests/results
>
> Plus, middleboxes that bridge HTTP/1.1 servers to HTTP/2 clients may need to
> transcode/decompress deflated data from broken servers that also get the
> APEC wrong.
>
> Otherwise all HTTP/2 clients will need to use heuristics to guess which
> algorithm the peer is using. From Sam Saffron on Stack Overflow[3]:
>
> "So, over the years browsers started implementing a fuzzy logic deflate
> implementation, they try for zlib header and adler checksum, if that fails
> they try for payload."
>
> [3]:
> http://stackoverflow.com/questions/388595/why-use-deflate-instead-of-gzip-for-text-files-served-by-apache
>
> My preference is to avoid this rats nest and require gzip only.
Received on Tuesday, 25 February 2014 21:03:04 UTC

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