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Re: Revisiting Authoritative Metadata

From: Robin Berjon <robin@w3.org>
Date: Tue, 26 Feb 2013 11:17:55 +0100
Message-ID: <512C8BD3.7020205@w3.org>
To: Larry Masinter <masinter@adobe.com>
CC: John Kemp <john@jkemp.net>, "Eric J. Bowman" <eric@bisonsystems.net>, Henri Sivonen <hsivonen@iki.fi>, "www-tag@w3.org List" <www-tag@w3.org>
On 26/02/2013 00:17 , Larry Masinter wrote:
> I did talk about this in
> http://tools.ietf.org/html/draft-masinter-mime-web-info-02
>
> but didn't get much TAG traction.

This document is a good start at outlining the issues, but I think that 
it perhaps covers too much ground as a conversation starter. There are 
many (related, but separable) issues treated there that might be simpler 
to discuss in isolation.

> 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.

I think that this conflates two issues: authoritative metadata and 
extensible/distributed type identifiers. I'm not suggesting that we 
throw the baby out with the bathwater: it would well be valuable to 
reuse MIME (or something like it) for magic numbers (or similar 
process). That would keep the system's extensibility while doing away 
with the issues with authoritative metadata.

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

Certainly, but that is a problem with identifying typing in general and 
isn't specific to the mechanism used to convey that information.

> 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).

Well, before looking at technical solutions for conveying additional 
information we have to agree on what information is useful. Versioning, 
for instance, I believe isn't:

     http://berjon.com/blog/2009/12/xmlbp-naive-versioning.html

-- 
Robin Berjon - http://berjon.com/ - @robinberjon
Received on Tuesday, 26 February 2013 10:18:07 GMT

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