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Re: Microsoft's "I mean it" content-type parameter

From: Jamie Lokier <jamie@shareable.org>
Date: Thu, 3 Jul 2008 14:29:32 +0100
To: Julian Reschke <julian.reschke@gmx.de>
Cc: "William A. Rowe, Jr." <wrowe@rowe-clan.net>, Robert Collins <robertc@robertcollins.net>, HTTP Working Group <ietf-http-wg@w3.org>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <20080703132932.GA1390@shareable.org>

Julian Reschke wrote:
> Many more clients to content sniffing, and the HTML5 draft suggests it's 
>  the right thing to do...

So this whole question can be rephrased thus:

   Are there significant numbers of servers out there which are
   serving content intended to be rendered as HTML (or other) with
   Content-Type: text/plain?

> >>I think its bogus - it requires every web site author in existence to
> >>change their site to fix a defect in MSIE. Thats got to be harder to
> >>deploy than just a hotfix to MSIE to not sniff at all.

Perhaps.  On the other hand, presumably the IE sniffing heuristic has
worked fine for many years with most sites, therefore it *doesn't*
require most site authors to do anything at all.

> >"For instance, if Internet Explorer finds HTML content in a file delivered
> >with the HTTP response header Content-Type: text/plain, IE determines that
> >the content should be rendered as HTML. Because of the number of legacy
> >servers on the web (e.g. those that serve all files as text/plain)
> >MIME-sniffing is an important compatibility feature."
> >
> >It would be very fun to see the example they cite, I sincerely doubt they
> >exist to any legitimate extent today.

What about all HTTP->FTP proxies?  FTP doesn't have Content-Type.  Do
proxies themselves add Content-Type by sniffing what they are forwarding?

I suspect this IE sniffing came out of compatibility with what the
browser must do when viewing FTP servers and local filesystems, by the
way.  On both of those, the browser must either sniff the content,
and/or sniff the filename, to decide the content type (and charset).

Also, it might it be invoked by servers which report *no* Content-Type?

> >Our friends crawling the web could probably give us hard numbers.

Hard numbers would be good.

-- Jamie


  I suspect the short history goes;
> >...
> 
> As a matter of fact, I can't even reproduce that *specific* case with 
> IE6 and IE7, see 
> <http://hixie.ch/tests/adhoc/http/content-type/013.html>. Not sure what 
> I'm missing here...
> 
> > ...
> >This makes no more sense than their lifting Content-Disposition into http,
> >but there you go, it's there.  Until more major MS customers move entirely
> >to Firefox or other alternatives, I don't anticipate this patchwork 
> >approach
> >changing.  And few content providers are so lucky as to dictate their
> >browser client.
> >...
> 
> Hm, what does this have to do with Content-Disposition?
> 
> >...
> 
> BR, Julian
> 
Received on Friday, 4 July 2008 08:53:24 GMT

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