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Re: Revisiting Authoritative Metadata (was: The failure of Appendix C as a transition technique)

From: David Sheets <kosmo.zb@gmail.com>
Date: Fri, 22 Feb 2013 03:36:34 -0800
Message-ID: <CAAWM5Tx=VrV4G03KqUaKybwrk3Xn=xFT5Sj7nNNAa0JQaDfXrw@mail.gmail.com>
To: Robin Berjon <robin@w3.org>
Cc: Larry Masinter <masinter@adobe.com>, Henri Sivonen <hsivonen@iki.fi>, "www-tag@w3.org List" <www-tag@w3.org>
On Fri, Feb 22, 2013 at 1:22 AM, Robin Berjon <robin@w3.org> wrote:
> On 22/02/2013 08:22 , Larry Masinter wrote:
>>
>> Perhaps the TAG finding on "Authoritative metadata" needs to be
>> re-reviewed and made into a consensus Req (and sniffing between
>> XHTML and HTML disallowed).
>
>
> I would support the TAG revisiting the topic of Authoritative Metadata, but
> with a view on pointing out that it is an architectural antipattern.
> Information that is essential and authoritative about the processing of a
> payload should be part of the payload and not external to it. Anything else
> is brittle and leads to breakage.

HTTP is a text protocol. HTTP messages are of type application/http or
message/http. HTTP messages include metadata regarding the properties
of the representation of the served resource including the media type
of the envelope's contents, the version of the representation, and
information about when the message expires.

How is telling the client everything it needs to know about processing
and storage external to the message? It's in the message.

How is this an antipattern? It's very standard and very unambiguous.

> The sniffing behaviour is a consequence of media types as an architectural
> construct, not an alternative to it.

Sniffing is brittle and leads to breakage as included metadata
regarding how to interpret the payload is ignored.

The sniffing behaviour is a consequence of an attitude of Big Browser
Knows Best regarding media types.

The alternative to this behaviour is respecting the media type as transmitted.

How is sniffing a consequence of following the protocol?

> (I say "should", not "must", because in situations in which both end points
> can agree upon a vocabulary then they can exchange information more
> efficiently by dropping essential data.)
>
> Further, I think that the TAG should take this occasion to issue a
> recommendation to people building formats that they include format
> identifying information as essential, typically with a magic number, first
> non-blank line, etc.

What occasion would that be?

Here's how to can tell you are receiving an HTTP message:
<http://www.w3.org/Protocols/rfc2616/rfc2616-sec6.html#sec6.1>

HTH,

David
Received on Friday, 22 February 2013 11:37:07 GMT

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