Re: XML Catalogs and Public Ids
Leigh Dodds scripsit: > [A]ccording to Section 7.1.2 of the spec if a system identifier can be matched > in the catalog then that will always be used; an accompanying public > identifier is only used as a fallback if the system id doesn't match > (or is unavailable) and the prefer setting is "public". So far so correct. > So public ids are > only useful if the system identifier isn't available. Not so. A system identifier matches only if there is a system, rewriteSystem, or delegateSystem entry in the catalog. So if there are none of these, then as long as prefer="public" is set (which it should always be), then public, rewritePublic, and delegatePublic rules are applied. The setting prefer="system" is really only useful for SGML backward compatibility. Historically, the SGML system id was generally a local one, whereas the public id was meant to be universal. XML has made the system id universal instead; nevertheless, XML Catalogs were meant to be semantically identical to TR9401 catalogs. > Given that you > have to provide both in XML, public ids seem pretty redundant. There are two cases in which a public id can exist without a system id: in a NOTATION declaration, and after delegating to a new catalog via delegatePublic (in which case the original system id is discarded). > Toying with the command-line resolver application shows behaviour consistent > with this reading. > > Everything I've read up to now set me up to expect the following: that > Public Ids would be preferred and that System Ids would be the fallback. > > What am I missing? > > . > https://www.oasis-open.org/committees/entity/specs/cs-entity-xml-catalogs-1.0.html > . http://xml.apache.org/commons/ > . > https://www.oasis-open.org/committees/entity/specs/cs-entity-xml-catalogs-1.0.html#s.ext.resx > > > ----------------------------------------------------------------- > 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> > -- John Cowan jcowan@r... www.ccil.org/~cowan www.reutershealth.com "If I have seen farther than others, it is because I was standing on the shoulders of giants." --Isaac Newton
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