W3C home > Mailing lists > Public > public-ws-addressing@w3.org > December 2004

Issue i0001 - Clarification of "identifier"

From: David Booth <dbooth@w3.org>
Date: Mon, 13 Dec 2004 00:14:56 -0500
To: public-ws-addressing@w3.org
Message-Id: <1102914896.3268.926.camel@nc6000.w3.org>

Unfortunately, the word "identifier" has more than one meaning.  

I believe Paco and Jeff are correct that there is a mathematical sense
of the word "identifier" in which identifiers are required to be unique,
i.e., if two identifiers are different, then they cannot refer to the
same thing.  (I cannot easily locate a citation for this sense of the
word, but I seem to remember this being discussed on the www-tag list at
w3.org a couple of years ago.)

I (and I think most members of the WS Addressing WG, judging by the
minutes of last week's meeting) have been using the word "identifier" in
the Web Architecture or programming language sense of the word, in which
two different identifiers can indeed refer to the same value, thing or
Web resource.

RFC 2396 defines the word "identifier" as:
   An identifier is an object that can act as a reference to
   something that has identity.  In the case of URI, the object is
   a sequence of characters with a restricted syntax.

Issue #1 is about the use of URI+RefProps in the RFC 2396 / WebArch /
programming language sense of the word: something that can act as a
reference to a Web resource.  In this context, the words "address" or
"reference" would be just as good.  (Then again, we may discover
ambiguities with those terms also!)

If anyone is interested in having EPRs be usable as "identifiers" in the
other, mathematical sense of the word (such that different "identifiers"
MUST reference different resources), then that should be raised as a
separate issue.


David Booth
W3C Fellow / Hewlett-Packard
Received on Monday, 13 December 2004 05:15:02 UTC

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