- From: John Tigue <jtigue@DataChannel.com>
- Date: Wed, 15 Jul 1998 15:21:52 -0700
- To: Jim Davis <jdavis@parc.xerox.com>, John Tigue <jtigue@DataChannel.com>, w3c-dist-auth@w3.org
<Jim> <snip /> > At 11:15 AM 7/15/98 PDT, John Tigue wrote: > >...the DTD could be modified to make it impossible to > >have attributes associated with the properties being requested > > I take it that you think the answer then is "yes", that this > restriction is > intended but was just never stated? </Jim> <John> I do believe it was intended but that's for others to say. </John> <Jim> > > If so, your proposed solution is overkill. If you want to restrict > property elements to being both empty and attribute-less, > it's fine to just > say so in natural language in the spec. I think it's fine if the DTD > overgenerates (to use a technical term). You can add additional > restructions in english or in EBNF if you really want precision. The > expressive power of the DTD language is too low, and if we > tried to define > the syntax so that we could ensure that every document that was valid > according to the DTD was also legal WebDAV, we'd have to > tweak the spec > considerably. </Jim> <John> As I said earlier in the thread: > (Perhaps this document is simply for use in any future WebDAV work) I am not suggesting that we go back and modfify what is already done. I am simply trying to point out that if this sort of issue comes up again in future WebDAV work then there is a solution. In this thread, we are talking about XML so I would use the (admittedly weak) existing power of DTDs to constrain the syntax just as I would use EBNF where appropiate. We already have XML 1.0 and parsers. By using what DTD syntax constraints we currently have, a parser can be used during developement as a debug tool in order to maximize interoperability. During developement, use a validating XML processor for spec checking and during deployment use simply a well-formedness processor for performance. By leveraging the "power" of DTDs we can increase interoperability. If a desired feature can be expressed equally well in prose and in DTD syntax then I would go for DTD; a DTD into a parser is more precise than spec prose into a human. The overgenerating feature (attributes) is one of the nice things about XML but, from Yaron's comments, I do not think that feature is desirable for PROPFIND. Too late for PROPFIND but NMTOKEN attributes are useful and would have been appropriate for PROPFIND, I believe. If this type of design choice faces us again, I would use NMTOKENs in attributes. </John>
Received on Wednesday, 15 July 1998 18:25:06 UTC