Re: XML Public Indentifier

[David Brownell <david-b@pacbell.net>]

Betty L. Harvey wrote:

> This is where I think XML drops the ball.  With a catalog file
> I can move my XML files anywhere I want and just change the
> reference in the catalog file.
>
> With XML, you have to explicitly include this information in
> your document.  Therefore, if you move files around, then your
> links are broken.

On the other hand, letting updated catalog files mask broken
(that is, invalid SYSTEM ids) document/DTD text is its own
source of problems.

I seem to recall that SGML allowed use of only PUBLIC identifiers,
so it didn't necessarily carry that risk unless both PUBLIC and
SYSTEM identifiers were provided.  (Or if systems were set up
to depend on mapping SYSTEM identifiers like PUBLIC ones.)

A better solution is to use only URNs as system IDs in XML, using
some URN resolution mechanism.  That's technically  isomorphic with
a "only use FPIs with a catalog" SGML-ish policy, and can leverage
the various URN resolution projects (instead of catalogs).  Plus, it
sure seems more web-oriented to use URIs exclusively!

- Dave