Re: agenda for ER TC teleconference 20010507

[jcowan@reutershealth.com]

Lauren Wood scripsit:

> 4) issue 21: I don't think the email we've seen covers the issues related to i
ssue 
> 21; Norm and John had the action item to send email about what the catalog res
olver 
> should actually do when handed a urn:publicid system identifier.

Norm says that system ids are system ids, and public ids are public ids, and
never the twain shall meet.  And fundamentally I agree.  But there is an
exception, which after all is the point of the Kipling poem!

(See http://www.geocities.com/Athens/Aegean/1457/poem3.htm)

The W3C culture, frankly, is hostile to public ids.  They aren't part of 
Web architecture, as has been said several times both publicly and privately.
The whole purpose of our creating publicid URNs is to be able to smuggle
public IDs into the W3C system, and then get them processed through existing
catalogs.

In order to achieve that, we need to allow references to urn:publicid:whatever
to match existing *public id* catalog entries.  That is best done by
understanding a system id of this form, and only this form (and a fortiori a
URI of this form, and only of this form) as really a public id.

By doing that, for example, we can give an XML Schema a public id, and then
reference it through an xsi:schemaLocation hint of the form urn:publicid:*.
By translating this URI to a public id, it can be looked up in a
public-id-based catalog, which eventually delivers a local or remote URI.

(Of course, by *existing* I really mean XML Catalog translations of existing
catalogs, either done in advance or on the fly by catalog processors.)

                "Ha' done! ha' done!" said the Colonel's son.
                "Put up the steel at your sides!
                Last night ye had struck at a Border thief --
                to-night 'tis a man of the Guides!"

-- 
John Cowan                                   cowan@ccil.org
One art/there is/no less/no more/All things/to do/with sparks/galore
        --Douglas Hofstadter