[whatwg] several messages about content sniffing in HTML
foolistbar at googlemail.com
Fri Feb 29 08:43:42 PST 2008
On 29 Feb 2008, at 16:33, Julian Reschke wrote:
> Geoffrey Sneddon wrote:
>>>> It seems like the HTTP spec should define how to handle that, but
>>>> the HTTP working group has indicated a desire to not specify
>>>> error handling behaviour, so I guess it's up to us.
>>>> IE and Safari use the first one, Firefox and Opera use the last
>>>> one. I guess we'll use the first one.
>>> Isn't the fact that FF and IE disagree here an indication that
>>> this doesn't need to be specified?
>> Things aren't specified well enough until I can write an HTTP UA
>> that can work in the real world (which, as someone dealing with
>> feeds, I can tell you need without question support for content-
>> type sniffing) from reading specifications without having to
>> reverse-engineer anything.
> Doesn't seem to apply to this case.
> A duplicate Content-Type header response indicates that the response
> is invalid.
And guess what? Users don't like error messages. I want to know how to
deal with it without having to look elsewhere (from the spec).
> Apparently, most browsers accept the response anyway, some of which
> picking the first value, others the second. Both behaviors seem to
> be acceptable to users.
> So there's nothing you *need* to reverse engineer in this case.
A page (<http://www.toledoblade.com/apps/pbcs.dll/section?Category=RSS01&mime=XML
>) that I came across recently had:
Using the first would break badly. I guess it seems to work because of
content-type sniffing on an unknown (and invalid) header (or, as many
feed readers do, totally ignoring it, with the exception of any
charset parameter). Without content-type sniffing, that HTML 5 now
allows, you need the last.
But as James says: how do I know that which behaviour I choose doesn't
matter until I reverse engineer browsers to discover that?
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