norman.walsh.name: Comments on /2006/12/18/rddl http://norman.walsh.name/2006/12/18/rddl/comments.atom 2006-12-19T11:45:10Z Comment 1 on /2006/12/18/rddl http://norman.walsh.name/2006/12/18/rddl#comment0001 2006-12-19T01:53:44Z 2006-12-19T01:53:44Z C. M. Sperberg-McQueen 82d3090f904a99741da6a026beb35d0d2ab966b5 http://www.w3.org/People/cmsmcq

I'm not sure whether it counts as "the wild", but there are several namespaces defined by W3C specs which use RDDL documents at their namespace locations. (You knew that already, of course.) On the whole, I think that's a Good Thing.

That said, I can't help regretting that RDDL abuses XLink semantics so badly. It uses the simple link notation, which means the links claim that a particular relation exists between the resource they are pointing at and the contents of the link element. That seems clearly false: the only reason one has to be interested in the links in a RDDL document is that they express a relation between the resource they point at and the namespace whose name is the URI of the RDDL document. As specified, RDDL is a set of rules for systematically lying to XLink processors. When I have pointed this out to people who say they are deeply interested in semantics, they say "Oh, well, it's close enough." Which makes me very skeptical about the future of machine-processable semantics on the Web.

A second problem I have with RDDL is that it seems not to be able to say very coherently what it means by a 'nature' or a 'purpose'. Because of that, when I have to prepare a RDDL document I look for a model I can follow very closely, and I mostly limit myself to pointing at schemas.

But it's still the best alternative I've seen. As in: the only. So good luck to you in your effort to make it semantically sound.

 Comment 2 on /2006/12/18/rddl http://norman.walsh.name/2006/12/18/rddl#comment0002 2006-12-19T11:45:10Z 2006-12-19T11:45:10Z Norman Walsh 9f5c771a25733700b2f96af4f8e6f35c9b0ad327 http://norman.walsh.name/

Thanks, Michael. I know about some of the W3C namespaces. I've also heard that Microsoft is using RDDL now. I expect I can find more with a search engine. I'm hoping this essay gets me pointers not just to extant RDDL namespace documents but ones that are actually used by people and software.

Regarding your concern about the abuse of XLink, I have mixed feelings. On the one hand, your analysis is entirely sound. On the other, the use of URIs for role and arcrole clearly make the machine understandable meaning of the link clear. On the whole, an alternate syntax that didn't use XLink would probably be semantically cleaner.

As far as your concern about the meaning of nature and purpose, that might be more clear in the more complex model. Or not. When the TAG minutes are published, I'll add a pointer to them.