Let's change the thread. Instead of talking about whether XML and RDF are better and worse for preserving queries under structural change (since Paul has shown that, in principle, there's an equivalence), let's talk about the goodness! Here's a first cut (to be fleshed out). I asterisk the ones I'm not sure are true or that I can show: ****1) RDF, and RDF culture, has some good affordances for "more compatible" structural modeling. That is, one is more likely to get (structure) compatible models if you start with RDF and model "normally". Why? Well, there are insignificant representational choices that XML puts up front (e.g., attributes vs. elements) that have a big effect on queries. Also, since XML's model is of the *data* (not the world) there's less incentive to find "natural fits" (e.g., properties model relations whereas in XML nesting could model a relation or a hierarchy). I find this pretty weak. I've seen plenty of highly variant modeling. I have trouble believing that two people sitting down will reliably come up with anything similar. ****2) RDF allows you to keep everything in "one model". I.e., you can just keep adding stuff to your pile o triples and sort things out later. Is this actually a strength? In principle, you can do that in an xml database and you can have queries that span more than one document/ schema. 3) Inference can help with schema alignment. I believe this. Even consistency checking of classes can be helpful. See ICOM. Plus there are presentational benefits to a class hierarchy. Ok, ran out of steam and have no references. Feel free to add, question, or elaborate! Cheers, Bijan.Received on Wednesday, 2 July 2008 10:45:37 GMT
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