- From: Booth, David (HP Software - Boston) <dbooth@hp.com>
- Date: Fri, 25 May 2007 12:15:49 -0400
- To: <public-grddl-comments@w3.org>
- Cc: "Jeremy Carroll" <jjc@hpl.hp.com>, "McBride, Brian" <brian.mcbride@hp.com>
While I was preparing the message below, DanC replied to Jeremy's query on this, saying that the WG and TAG had considered this question, and an XML namespace on the root element *does* imply a certain set of semantics: http://lists.w3.org/Archives/Public/public-grddl-wg/2007May/0071.html FWIW, I agree with the TAG's position on this, so the only remaining question for the GRDDL WG is whether the GRDDL spec should include a warning about this. Actually, I think the best approach might be to include a brief explanation of this in the GRDDL primer. David Booth, Ph.D. HP Software +1 617 629 8881 office | dbooth@hp.com http://www.hp.com/go/software > -----Original Message----- > From: public-grddl-comments-request@w3.org > [mailto:public-grddl-comments-request@w3.org] On Behalf Of > Booth, David (HP Software - Boston) > Sent: Friday, May 25, 2007 11:50 AM > To: public-grddl-comments@w3.org > Cc: Jeremy Carroll; McBride, Brian > Subject: issue-dbooth-10: Does an XML namespace necessarily > imply semantics? > > > This is a personal comment -- not on behalf of HP. > > This is the formal submission of the comment Jeremy already > sent to the > WG on my behalf: > http://lists.w3.org/Archives/Public/public-grddl-wg/2007May/0061.html > > Does an XML namespace necessarily imply a certain set of semantics? > Suppose Freddy at example.org defines a convenient XML schema for > writing a person's legal residence ("a:primaryAddress") a > vacation home > address ("a:secondaryAddress"), such as: > > <a:root xmlns:a="http://example.org/AddressSchema.xml"> > <a:primaryAddress>25 Park St, Rochester, NY</a:primaryAddress> > <a:secondaryAddress>88 Spring St, Salem, MA</a:secondaryAddress> > </a:root> > > Freddy makes the XML schema definition downloadable from the namespace > URI, and separately provides prose documentation to his users > explaining > the meaning and purpose of a:primaryAddress and a:secondaryAddress in > his application. In essence, Freddy's app treats this document as > though it had made the following assertions: > > foo:_lucy foo:legalResidence "25 Park St, Rochester, NY". > foo:_lucy foo:vacationAddress "88 Spring St, Salem, MA". > > Later, Ralph needs a schema for billing and shipping addresses and he > notices that Freddy's AddressSchema has the exact form he needs: > a:primaryAddress could represent the billing address and > a:secondaryAddress could represent the shipping address. In other > words, Ralph wishes to reuse the syntax only. (This is analogous to > implementation inheritance in OO programming.) Raph notes that an XML > schema only defines the structure of a document -- not the > semantics -- > and the namespace spec does not seem to say anything about > the semantics > of a namespace either. Ralph reuses Freddy's schema by reference, and > provides separate prose documentation to his users explaining that the > syntax (only) of Freddy's schema is being reused but the semantics are > to be the semantics specified by Ralph. Example: > > <a:root xmlns:a="http://example.org/AddressSchema.xml"> > <a:primaryAddress>123 Winter St, Palo Alto, CA</a:primaryAddress> > <a:secondaryAddress>444 El Camino, San Diego, > CA</a:secondaryAddress> > </a:root> > > In essence, Ralph's app treats this document as though it had made the > following assertions: > > fum:_desi fum:billingAddress "123 Winter St, Palo Alto, CA". > fum:_desi fum:shippingAddress "444 El Camino, San Diego, CA". > > Later Freddy decides to update his XML schema document at > http://example.org/AddressSchema.xml to declare a GRDDL transformation > in the namespace document such that the above example would be GRDDL > transformed to RDF. Ralph may have no knowledge of GRDDL and may be > unaware of this change, but suddenly Ralph's documents gain the > semantics of Freddy's documents according to the GRDDL spec. > Questions > Was Ralph wrong to re-use Freddy's namespace and syntax schema while > imparting his own semantics to that schema? If so, what spec forbids > this? (Presumably this is a question for the W3C TAG.) > > My own view at present is that a namespace should be viewed > as implying > the semantics that its owner declares, regardless of whether GRDDL is > used. Hence, Ralph should not give his document different semantics > than Freddy somehow specifies via his namespace document. If Freddy's > semantics are not clear to Ralph, then Ralph should not use Freddy's > namespace, due to the risk of guessing wrong. > > However, since I do not at present see anything in the > namespace spec or > the WebArch that forbids this kind of syntax-only reuse, perhaps the > GRDDL spec should address the possibility of its allowance. > If so, what > should the GRDDL spec say? > > Option 1: Add some warning text in the spec. This might include > suggesting that GRDDL aware agents check last modified times > on docs and > namespace docs, but this does not seem like it would be reliable. > > Option 2: Record a postponed issue (possibly to be referred > to the TAG). > > At present I think either option would be okay. > > > David Booth, Ph.D. > HP Software > +1 617 629 8881 office | dbooth@hp.com > http://www.hp.com/go/software > >
Received on Friday, 25 May 2007 16:18:29 UTC