Identifying XML Document Types (was XML media types
W. Eliot Kimber
eliot at dns.isogen.com
Fri Jan 15 20:30:15 GMT 1999
At 03:12 PM 1/15/99 -0500, Simon St.Laurent wrote:
>Perhaps I'm being a little too hard, but none of these solutions seem
You're correct: none of them are viable, because they do not create
self-describing objects. What is needed is a mechanism that allows a
document to unambiguously point to the definition of what it is, from which
applications can then determine the right thing to do. MIME types go a
long way, but they are managed outside the document, leaving open the
question "how do I know what MIME types to associate with a document?".
Note that the external identifier of the doctype declaration, if there is
one, *CANNOT BE THIS POINTER* because it simply identifies an entity with
some declarations in it, from which you can reliably infer nothing.
Schema-use declarations (many have been proposed) and architecture use
declarations (the new PI-based syntax) are examples of workable solutions
because they point to authoritative definitions of what the rules for the
document are. Note that architecture use declarations are standardized
today and trivially easy to implement support for. The external identifier
for the architecture definition itself can be anything, including public
IDs and MIME types.
W. Eliot Kimber, Senior Consulting SGML Engineer
ISOGEN International Corp.
2200 N. Lamar St., Suite 230, Dallas, TX 75202. 214.953.0004
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