Re: The XML Schema GRDDL Story

On Tue, 2004-12-14 at 11:26, Eric Miller wrote:

> I'm still sort of on the fence about following xsi:schemaLocation, with 
> a slight preference to include this capability. But if you guys think 
> not, at least @@'ing this issue in an updated GRDDL note is probably 
> worthwhile.

To be really seaworthy, it's good if schema-aware software
can

  - accept pointers to schema documents as part of its
    invocation
  - check the namespace URI for a schema document
  - check the namespace URI for a RDDL document, and
    find a schema document there if the RDDL points to
    one
  - follow the hints given in schemaLocation attributes
  - consult a local or built-in store of information

preferably giving the user some control over which of
these happens when, and whether failure at any stage
should mean the processor continues (oh, well, we didn't 
get any components from that source, I'll work without
them) or not (fatal error, you told me to find XHTML
components or die -- I didn't find them, now I'm 
dying).

Demos, and even some production applications, can get
by without all of these.  But if the service can ONLY
use schema documents found at the namespace name, then
it does seem to mean no one can doctor an existing
schema document for a namespace owned by somebody else 
and see what the service would do.  So if I want to
experiment with (say) annotation of the OAI or Dublin
Core schemas, my choices are (a) to hack into their
servers and replace their copy of their schema documents
with my own, or (b) to fudge all of my examples by
replacing references to their namespace with references
to a namespace I own, or where I can at least control
what gets served from the namespace name, or (c) I can
try to persuade the owners of those namespaces to
humor me and put my experimental version of their
schema on their server where all the world can find it.
None of these three seems quite right for me.  

I think the idea that for any namespace there is
or should be a single schema document is -- well, it
seems awfully closed-worldish to me.  

So I'd encourage more flexibility in locating 
schema documents.

For the masochistic, more on locating schema components at
http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2004Dec/0012.html
(towards the bottom, proposed content of appendix
Y.s) and http://www.w3.org/People/cmsmcq/2001/schema-resolution

Michael