Re: locating schemas via public ids

[Paul Grosso <pgrosso@arbortext.com>]

At 12:50 2001 01 24 -0500, Norman Walsh wrote:
>Paul suggested (and then retracted) an extension to the xsi:schemaLocation
>hint that would have allowed public identifiers:
>
>	 xsi:schemaLocation='
>             "-//OASIS//DTD DocBook XML Schema V4.1.2.2//EN"
>             docbook.xsd
>	     http://www.oasis-open.org/docbook/xmlschema/4.1.2
>             docbook.xsd'>
>
>I was concerned that the public and system identifiers could not be
>disambiguated in that string, but Paul's intent (IIUC) was that a
>quoted string was a public identifier and an unquoted one was a system
>identifier.

No, that's not what I said.  (For details of what I said, see
my earlier email, but it's obvious an example is needed.)

I'm not sure how to read your example, but let's start with:

	 xsi:schemaLocation='
	     http://www.oasis-open.org/docbook/xmlschema/4.1.2
             docbook.xsd'>

which has a single namespace-name/external-id pair.  My
suggestion would keep the namespace-name/external-id pairing
concept, but it would allow any member of any pair
to be optionally quoted.  Therefore, the following would
be allowable and equivalent to the above:

	 xsi:schemaLocation='
	     http://www.oasis-open.org/docbook/xmlschema/4.1.2
             "docbook.xsd"'>

Now assume we want to add info about the public id to the
external-id member of the pair in the above example.  My
suggestion would augment the allowable syntax for the 
external-id part to allow the specification of a public id
(as well as the system id).  In my suggested syntax, it would read:

	 xsi:schemaLocation='
             http://www.oasis-open.org/docbook/xmlschema/4.1.2
             "PUBLIC '-//OASIS//DTD DocBook XML Schema V4.1.2.2//EN'
             docbook.xsd"'>

where the entire double-quoted string is the second member of
the pair and it consists of a string that looks just like the
external identifier of a doctype decl would look.  The problem
is that this requires three levels of quotes, so the innermost
ones end up having to be escaped as ' in my example.

I think it "works", but it may be considered too ugly to be
acceptable.

paul