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Actually, I've been wondering why W3C XML Schema doesn't use processing instructions instead of the xsi:schemaLocation attribute. Multiple PI's seem to be better than a space-seperated list of URI's. Can somebody point me to the rationale? Thanks, Brian Michael Brennan wrote: > While tinkering with XLink and RDDL, I had an idea that I thought I'd toss > out on this list. I'd be interested to know if there have been similar > proposals in the past. > > A number of specs put forward specialized mechanisms for associating > external resources with a document for a specific purpose. For example, XML > Schema gives us the "xsi:schemaLocation" attribute, XML Catalog gives us the > "oasis-xml-catalog" PI, and for associating stylesheets, we have the > "xml-stylesheet" PI. It seems like these could be unified into one > generalized mechanism by building upon XLink and RDDL constructs. You > couldn't use XLink syntax directly since these examples all must be declared > before the document element or on the document element itself. But it seems > to me that one could designate a generalized PI that mimics XLink simple > links that could achieve the desired result. > > For example, the attribute "xsi:schemaLocation='http://foo/bar foobar.xsd > http://yadda/yadda yadda.xsd'" could become: > > <?xml-link role="http://www.w3.org/2001/XMLSchema" > arcrole="http://foo/bar" href="foobar.xsd"?> > <?xml-link role="http://www.w3.org/2001/XMLSchema" > arcrole="http://yadda/yadda" href="yadda.xsd"?> > > The PI <?xml-stylesheet type="text/css" href="style.css"?> could become: > > <?xml-link > role="http://www.isi.edu/in-notes/iana/assignments/media-types/text/css" > href="style.css"?> > > The PI <?oasis-xml-catalog catalog="http://example.com/catalog.xml"?> could > become: > > <?xml-link role="urn:oasis:names:tc:entity:xmlns:xml:catalog" > href="http://example.com/catalog.xml"?> > > This seems to me better than the current situation for the following > reasons: > * Provides a consistent, extensible mechanism for these sorts of processing > directives. > * Leverages namespaces and URIs for identifying the intent and purpose of a > directive. > * Does not clutter up the document's infoset with processing directives as > attributes do. > > Is this a reasonable idea or am I off my rocker on this? Have there been > similar such proposals? > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org <http://www.xml.org>, an > initiative of OASIS <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the subscription > manager: <http://lists.xml.org/ob/adm.pl> >
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