Re: Catalog Requirements (resend after 2-day bounce)

[Norman Walsh <ndw@nwalsh.com>]

/ Terry Allen <tallen@sonic.net> was heard to say:
| What bad happens if we just add a URI>URI function?  (I don't
| know, I'm asking to see whether the simplest solution would 
| work.)

I don't know that anything bad happens, but I have three concerns.

1. At the moment, catalog lookup is non-recursive and terminates at
the first match. I worry that if we add a URI keyword, we'll find
users that want lookup to be recursive: map the public id to a URN
(via PUBLIC), then map that URN to a URL (via URI) and I don't think
we want to go there.

2. We're going to introduce a thorny precedence question. If a URI
matches both a SYSTEM keyword and a URI keyword, which one wins?
There are four answers, I think:

  a. SYSTEM always wins
  b. URI always wins
  c. SYSTEM and URI are equal, the first one encountered wins
  d. It depends on what you're looking up

The last is maybe the most "correct", but it's also the most difficult
to explain. And we'll have to answer the question: if you attempt
SYSTEM lookup and fail, can you then (in conformance) attempt URI
lookup?

3. I think it will open the door to the question of how many different
sorts of URIs are there, and shouldn't I be able to map them all
differently?

  URI "uri" "uri"
  NAMESPACE "uri" "uri"
  STYLESHEET "uri" "uri"
  SCHEMALOC "uri" "uri"
  ...

And I don't know if I want to go there or not. I want to keep this
simple and as close to TR9401 as is practical.

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@East.Sun.COM | ...it is significant that we are called the
XML Technology Center     | 'information society' -- not the thinking
Sun Microsystems, Inc.    | society, not the deliberative society, not
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