xml-dev - Re: XCatalog proposal draft 0.1

[John Cowan <cowan@locke.ccil.org>]

Paul Grosso scripsit:

> System ids have been pretty obvious in most cases for decades.
> While it is true that 8879 allows system ids to be almost anything,
> all the SGML systems I've seen figure a regular looking system id
> is a file name, and that works fine.  In fact, it wasn't until
> the third version of the SGML Open Catalog TR9401 that we added
> mapping of system ids.

But in XML *that doesn't work*, at least not in all cases.  Systemids
are URIs, and a systemid that looks like "foo.bar" is a relative
URI, not necessarily a local file name.  If you are processing
a local file, it probably will be a local file name, but if you
are processing a document fetched by HTTP, then it will be another
document fetched from the same directory of the same server.

This is why I believe systemid mapping is inappropriate for XML.
When a document author provides a URI, he or she has a right to assume
that the document processor will take that URI at face value.

> The real reason for the SGML Open Catalog was because 8879 did not
> define a way to map public ids into much of anything.  And neither
> does XML.

Yes, and that's the property I want to keep.  The four entry types
Map (PUBLIC in Socat syntax), Catalog, Delegate, and Base provide
what's needed for an infrastructure, analogous to DNS, to make
public IDs truly *public*.

-- 
John Cowan	http://www.ccil.org/~cowan		cowan@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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