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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Designing XML to Support Information Evolution
 Hierarchical databases failed for a reason. Treating XML as a hierarchical data modelling mechanism especially in teh context of databases is inviting failure that anyone who's taken a database class in the past twenty years can warn you against. -- PITHY WORDS OF WISDOM There are always two solutions to the problem: yours and the boss's. ________________________________ From: Michael Champion [mailto:mc@x...] Sent: Mon 5/17/2004 8:28 AM To: xml-dev DEV' Subject: Re: Designing XML to Support Information Evolution On May 17, 2004, at 10:20 AM, Roger L. Costello wrote: > > 1. How you structure your information in XML has a tremendous impact > on the processing of the information. > > 2. Hierarchy makes processing information hard! There exists a > relationship between hierarchy of information and the complexity of > code to process the information. The relationship is roughly: the > greater the hierarchy, the greater the complexity of code to process > the information (Some hierarchy is good, of course. But the amount > of hierarchy that is good is probably much less than one might > imagine, certainly less than I thought, as described above.) > > 3. Flat data is good data! Flatten out the hierarchy of your data. > It makes the information flexible and easier to process. > > 4. Order hurts! Requiring a strict order of the information makes for > a brittle design. It is only when I allowed the lots and pickers to > occur in any order that the flexibility and simplicity kicked in. > > Comments? /Roger I'm wondering if you haven't rediscovered the relational model? (Or at least you've discovered the importance of "normalization" in the relational sense even in the XML context). But why bother with XML at all (except maybe as a data interchange format) here? Wouldn't a relational reporting tool be much easier than XSLT with this data structure? C.J. Date gave a speech recently http://searchdatabase.techtarget.com/originalContent/ 0,289142,sid13_gci962948,00.html complaining that XML is trying to take over the world. Maybe he has a point :-) I certainly don't agree with all he's saying, but if you are modeling data rather than exchanging documents, I would think that the relational model would be the starting point until you run into its walls. Clearly if flexibility is paramount, order and hierarchy are a pain, and there's not much gain *if* you have unique identies for everything and the identity is all you need to know to figure out what to do with the information. On the other hand, if *context* is important, i.e. the intepretation / semantics / meaning / processing paradigm of some bit of information depends more on where it stands in relation to other information, then order and hierarchy are critical. That's where the XML "data model" (by which I mean "fairly deeply hierarchical labelled trees in which order is preserved", not the InfoSet per se) comes into its own. ----------------------------------------------------------------- The xml-dev list is sponsored by XML.org <http://www.xml.org>, an initiative of OASIS <http://www.oasis-open.org> The list archives are at http://lists.xml.org/archives/xml-dev/ To subscribe or unsubscribe from this list use the subscription manager: <http://www.oasis-open.org/mlmanage/index.php> 
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