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RE: Revisiting Authoritative Metadata

From: Larry Masinter <masinter@adobe.com>
Date: Mon, 25 Feb 2013 15:17:03 -0800
To: Robin Berjon <robin@w3.org>, John Kemp <john@jkemp.net>
CC: "Eric J. Bowman" <eric@bisonsystems.net>, Henri Sivonen <hsivonen@iki.fi>, "www-tag@w3.org List" <www-tag@w3.org>
Message-ID: <C68CB012D9182D408CED7B884F441D4D1E87D76850@nambxv01a.corp.adobe.com>
I did talk about this in 
http://tools.ietf.org/html/draft-masinter-mime-web-info-02

but didn't get much TAG traction. 

Another example:
When Adobe attempted to introduce the "DNG" standard (Digital Negative)
http://en.wikipedia.org/wiki/Digital_Negative
there were problems with clients "sniffing" that image/dng was 
a "tiff" file and sending it off to a TIFF interpreter. This is a general
design pattern where you want to use a specialization of an existing
type (magic number at all), and where the receiver handling should vary
depending on the content-type.

The fallacy is believing that a given piece of content "is" in a single
content-type, when often it is ambiguous.


In general, polyglot and generic/specific overlaps of content-type is cause
for asserting that sniffing alone is broken for most content-types, because
the inventors of the content-type have not allowed for any indication of
version/specialization (like not having any HTML version type).

We're used to files retaining their file types by file extensions when saving
to disk, and it's common in most operating systems.  I think a move to fix
"mime types" to make file extensions actually registered, and used as a way
of translating content-type into file extension and back would be helpful,
but a lot of work.



> -----Original Message-----
> From: Robin Berjon [mailto:robin@w3.org]
> Sent: Monday, February 25, 2013 9:09 AM
> To: John Kemp
> Cc: Eric J. Bowman; Larry Masinter; Henri Sivonen; www-tag@w3.org List
> Subject: Re: Revisiting Authoritative Metadata
> 
> On 25/02/2013 17:40 , John Kemp wrote:
> > The reason that text/plain vs. text/html comes up so often is that it is
> > a very clear description of one problem with sniffing - that the author
> > intended the representation to be displayed as text without HTML
> > interpretation.
> 
> I'd be less charitable. I think that this example keeps coming up
> because proponents of authoritative metadata cannot think of any other
> example :)
> 
> I'd be interested in being proven wrong though!
> 
> > Although I agree that metadata sent from the server is less
> > authoritative than one would hope, I do not agree that a user-agent can
> > even accurately represent the wishes of the user in this case, let alone
> > comply with them.
> 
> Well, there's <plaintext> for that if you're sure that that's what you
> want. For all the other cases it would seem that View Source can work.
> 
> --
> Robin Berjon - http://berjon.com/ - @robinberjon
Received on Monday, 25 February 2013 23:18:21 GMT

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