XCatalog proposal draft 0.1

John Cowan cowan at locke.ccil.org
Tue Jul 28 17:22:17 BST 1998

Murray Altheim scripsit:
> In order to be a legal URL (and hence a legal
> URI), relative systemIds must be first qualified by a base URL. If I
> follow the spec to the letter, relative URLs must make system assumptions
> to obtain the base URL, which in some cases should be resolved via
> catalog.

Clause 3.3 of RFC 1808 says (in part):

# If no base URL is embedded and the document is not encapsulated
# within some other entity (e.g., the top level of a composite entity),
# then, if a URL was used to retrieve the base document, that URL shall
# be considered the base URL.

So a systemid that is a relative URL is normally to be interpreted
as relative to the URL of the document.  This is only problematic
in the case of the main document entity not having an URL (e.g.
standard input).

> I disagree with John's assertion that 'URNs are not defined'. I answered
> Paul Prescod's similar statement showing that URN specs do exist [URN],

Unfortunately, I can't dereference that URL.  Is there a copy somewhere
that is publicly accessible?

> with IETF RFCs for syntax and resolution, as well as working
> implementations. That vendors haven't yet implemented support is another
> matter entirely.

I grant you syntax.  The only RFC'ed resolution protocol is an
Experimental protocol, and the only two other relevant RFCs are
requirements and principles.  That hardly constitutes a robust
infrastructure definition.

John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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