xml-dev - Re: URI concerns continue

["Simon St.Laurent" <simonstl@simonstl.com>]

At 09:41 AM 7/11/00 -0400, Michael Mealling wrote:
>Just because you have an incorrect perception of the use of something
>doesn't mean that everyone else is wrong. URIs identify Resources
>in the abstract. That is their definition. You don't get to 
>redefine that simply because your experience is limited to the
>http scheme and some counter-productive, SGML-ish, bifurcation of
>public vs system identifiers.

Thanks, Michael.  It's always nice to be told that I'm wrong.  Of course,
since I'm calling URIs a quicksand foundation, I suppose I should expect
some irritated responses.

My experience is not limited to the http scheme, I'm afraid, though I think
I may have a better understanding of the public expectations surrounding
that scheme than some wise fellows.

>Any identifier can use be used to retrieve something. Its called a
>database lookup. You can do lots of things with an identifier: use it
>as a key to a database, use it to disambiguate something are two of the
>most important.  Those two functions are not mutally exclusive or 
>incompatible,

They are, however, severely underspecified, and the current uses of URIs in
XML specifications set no such expectations for those features.  As we've
found, even simple comparison is lacking in RFC 2396.

>> Does your placement of schemas at namespace URIs make you a hijacker?  I'd
>> say it very well might.
>
>If he has the assignment authority over that identifier used in that
namespace
>then no he isn't....

He's making additional claims about the usage of those URIs which are not
in the specification.  If I was in a bad mood, I'd call it 'embrace and
extend'.

>If you choose to name your namespace badly or in such a way as to make
>it difficult for someone to learn about your namespace then that's your 
>problem (or your intent). Its not the problem of xml namespaces or URIs....

The specifications leave open an astounding number of ways to use these
things badly.  It's the problem of the namespace specification's failure to
limit and define the tools provided by RFC 2396, which itself does very
little defining.

>> >In some cases, the abstraction is a static entity body.
>> >http://www.ietf.org/rfc/rfc2396.txt is such an example.
>> >But this is not the general rule -- it is a special case.
>> 
>> It's not even the general rule that there is an entity body.  In fact, I'm
>> not sure that there is a general rule beyond the existence of the syntax.
>
>The general rule is defined based on the scheme. But you know that
>all schemes identify some Resource. Its up to you to pick a URI that
>makes sense for what you're trying to do. If you pick badly then
>its your fault. Don't blame the infrastructure for giving you the
>freedom to cause problems for yourself...

I'd suggest that the builders of infrastructure would be wise to stop
building on quicksand and then blaming the unlucky victims.

>> This doesn't seem like an appropriate foundation for the kinds of
>> non-retrieval tasks URIs are being asked to do in various (namespace,
>> schema, XLink) XML contexts.
>
>Why not? You just want a name right? urn:oid:1.3.6.1.4.1.5 sounds
>like it covers the bases to me...

I agree.  Perhaps Namespaces in XML should have used URNs only.

Simon St.Laurent
XML Elements of Style / XML: A Primer, 2nd Ed.
http://www.simonstl.com - XML essays and books