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Re: ISSUE-58: Scalability of URI Access to Resources

From: Norman Walsh <ndw@nwalsh.com>
Date: Thu, 23 Aug 2007 10:20:35 -0400
To: www-tag@w3.org
Message-ID: <m27inm1gek.fsf@nwalsh.com>
/ Chimezie Ogbuji <chimezie@gmail.com> was heard to say:
| 1. http: != dereference
[...]
| I believe the appropriate recommendation, guideline, etc.. would be
| one which includes a clearly articulated set of scenarios which
| demonstrate when 'arbitrary' HTTP dereference (though not mandated) is
| useful for automatons/agents and when it might not be so useful (XML
| namespaces, for example).

Perhaps. I'm inclined to say that agents should dereference a URI when
they need to and not when they don't. I'm not sure how to describe
"need" in an application-independent way.

The RDF case, like the XML validation case, is interesting because the
agents in question are likely to "need" something else (an ontology
description or a schema, respectively) in order to continue
processing.

| 2. The dereference problem is scheme independent
|
| The second part of this particular point assumes there will
| *inevitabely* be a need to dereference these (insert your favorite
| other scheme here) URIs.  This is not always true, especially when the
| URIs in question are RDF URIs. 

No, my point wasn't that there will inevitably be a need to
dereference them. The point I was trying to make was that *if* you
need to dereference them, you need to dereference them and the scheme
of the URI isn't really the important part.

If you *don't* need to dereference them, then this whole issue will
never arise for you and you can use http: URIs (see point 1).

| applies to all usage of URIs.  RDF URIs have a different usage pattern
| than the typical Web scenario and the literature should consider this
| divergence.

A different usage pattern from web browsing by a human being, perhaps,
but do you really think it's different from what other software agents
do, for example, XML validation in an application server?

| In addition, the dereference problem is not entirely scheme
| independent.  Actually, it *only* applies to those URI schemes which
| are (formally) associated with a transport protocol (ironically, the
| same scheme(s) which are the subject of suggestion for their pervasive
| use).

I don't agree. There's no transport protocol associated with urn:
scheme URIs, but if you need to dereference them, then you need to
dereference them. Granted, you'll have to use a different
architecture, but at the end of the day, you'll still be banging on
some server somewhere for the representation and this issue will arise..

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com> | A child becomes an adult when he
http://nwalsh.com/            | realizes he has a right not only to be
                              | right but also to be wrong.--Thomas
                              | Szasz

Received on Thursday, 23 August 2007 14:19:26 GMT

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