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

From: Eric J. Bowman <eric@bisonsystems.net>
Date: Sun, 24 Feb 2013 12:20:45 -0700
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>
Message-Id: <20130224122045.e0bf7cd2c352e6205b82d376@bisonsystems.net>
Robin Berjon wrote:
> 
> 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.
> 

Antipattern?  This *is* the architecture.  Unlike FTP, the HTTP and
Gopher protocols introduced the notion of sender intent, decoupling
the rendering of a file from its extension or magic number.  Unlike
Gopher, HTTP re-used MIME, avoiding the requirement of versioning the
protocol every time a new format (which may have use beyond the Web) is
introduced ('h=html' is widely implemented in Gopher, not specc'd).

Expressed formally, this "late binding of resource to representation" is
fundamental to Web architecture; its implementation in HTTP is the
Content-Type header.  Without it, there is no mechanism to express
sender intent, even one that's somewhat ignored in practice.  I won't
equivocate on thinking this to be a good thing...

Given any architecture which supports a variety of data formats, if
intermediaries are to be allowed to participate, they can't be required
to decode (sniff) the payload to determine the format anyway, without
requiring them to have high-end CPUs.  As it is, the Web scales nicely,
right down to my decade-old desktop embedded-Linux squid router.

The alternative to Authoritative Metadata, is for the TAG to deprecate
sender intent altogether; iow, redefine what Web architecture *is*.  By
committee, going against the organic evolution of the Internet and Web
as formalized, not defined, in Roy's peer-reviewed dissertation...

-Eric
Received on Sunday, 24 February 2013 19:21:08 GMT

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