Doug,
I fear that there may be some things that you misunderstand about XML
namespaces and schemas.
Every (and I mean EVERY) XML namespace and schema is identified by a
URI. The URI contains no semantic information, but serves entirely to
disambiguate the identifiers. Think of it as a distributed
collision-avoidance mechanism. It is traditional to use http URLs as
these URIs, and to ensure that the use is done with the blessing of the
owner of that position in the http name space.
An XML Schema, once published, is forever immutable. (Yes, I mean
forever.) You don't get to revise it, period. If you later need
extensions, you publish them in a new namespace with a new XML schema.
So, the contents of the schema can certainly be baked into code. It is
never necessary for someone interpreting the schema to use HTTP and
fetch data. There is no requirement that people who publish schemas
maintain HTTP servers that answer that URL. (Many do, but only as a
courtesy to humans who are wondering what the URI means.)
-- jimbo
-----Original Message-----
From: owner-ietf-mxcomp(_at_)mail(_dot_)imc(_dot_)org
[mailto:owner-ietf-mxcomp(_at_)mail(_dot_)imc(_dot_)org] On Behalf Of Douglas
Otis
Sent: Friday, May 21, 2004 5:43 PM
To: Bob Atkinson
Cc: Eric A. Hall; Arnt Gulbrandsen; Yakov Shafranovich; IETF MARID WG
Subject: RE: suggested new RRtype experiment
On Fri, 2004-05-21 at 17:19, Bob Atkinson wrote:
If this schema is fixed as part of the specifications, then adding
any
reference other than the registered version (document type) is not
needed nor desired. This http link is offering a mechanism for ad
hoc
modifications or extensions. It is not, by any means, for the
programmer's convenience.
You're quite wrong about this.
The schema used in the URI isn't important. The only criteria used to
choose the existing Caller ID namespace was that it be short.
But the fact that there is a URI in the document, which names the XML
namespace in which the elements etc are found, is quite critical.
Not having a URI means there MUST be a predefined definition within a
specification referenced by a much simpler and smaller tag. Only the
tag is critical. Having a URI is highly problematic if to lock down
definitions. IANA already has a registry for these definitions. If
these definitions change, the tag changes per the specification that
provides the changes. As these specifications are to be used to compile
a parser, it is important these specifications not change in an ad hoc
fashion or the model of operation changes in a dramatically bad way.
-Doug