[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Re: ID/IDREF makes XML generation NP-hard
On Fri, 4 Apr 2003, Rick Jelliffe wrote: > From: "Murali Mani" <mani@C...> > > My point is that Henry showed something different: it applies only to DTD > containing fixed or defaulted IDs or IDREFs. So while it applies to DTDs > in general, it does not apply to *most* DTDs, and it is trivial to figure out > if the DTD has fixed or defaulted IDs or IDREFs. I concur. Henry's example was not proper use, the only thing is no one has defined proper use so far.. I like ID/IDREF -- it allows traversing relationships using path expressions.. Actually, we can convert any ER model to XML w/o using any foreign keys, purely using ID/IDREF, which will imply we can perform most queries w/o using joins, and hence lesser mistakes in writing queries..?? Can I request you to take a look at http://www.cs.ucla.edu/~mani/er03/modeling.pdf -- this is a quite easy to read paper and should motivate very well, it is still under preparation, though the ideas, trade-offs etc, I believe, have come out quite clearly.. > I have seen people use Henry's analysis as some kind of proof that ID/IDREF > itself is bad, and I just cannot see the connection, if indeed it says nothing > about normal use of ID/IDREF. (Who on earth uses fixed or defaulted IDs: > it is very strange?) > > I think both the DSDL group at ISO and the W3C XML Schema group > would be very interested in insight on how to move forward with keys. I am focussing on this, and trying to understand what should be good ways of doing things. I have sufficient encouragement and motivation to do a good job. I hope something good will come out of our work.. > > More work needs to be done with respect to constraint specification. > > Yes indeed. Which is one reason I suspect the Schematron approach, > of just levering what is convenient and comprehensible, is appropriate > at the moment: if the properties of paths to trees are still active research. cheers and regards - murali.
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