Re: [Hardhats-members] Alternate databases?

[Gregory Woodhouse]

On Jun 15, 2006, at 4:32 PM, CamSchlehuber wrote: There have been two very different approaches to using the VHIM.  One is used in the FHIE (Federal Health Information Architecture) and the BHIE (Bi-directional Health Information Architecture ... to move data in both directions between VA and DOD).  That approach keeps the data structures very light-weight and can support virtually any version of the model.  The information structure for requesting and passing data is computed at the time of the request and response.  It proved quite useful when the timetable for delivering FHIE was so short that the code had to be done before the model was finished!  It's also vaguely reminiscent of the HL7v3 approach to self-describing messages, at least if I understand your description (!) correctly. The second approach is to use the VHIM to generate SQL DDL for a given model version with every relationship hard-wired into the tables.  (In my opinion, an extremely brittle approach I'm inclined to agree. ... It's how VistA was built in the early stages.  Yes. Some pioneering work by Bob Andrews and by Doug Martin showed a much more agile approach!  Unfortunately, in VA this work hasn't seemed to catch hold.) It would be interesting to hear more about this. I've seen some approaches (often very interesting) to integrating the object and database approaches, but nothing that I've found entirely satisfactory. Then again, I've had the nagging sense that the whole object oriented approach isn't sufficiently general. Consider that object oriented modeling gives us various types of relationships and hierarchies ("is-a", "has-a", "uses", etc.) but provides no convincing framework that encompasses them all. UML tries to do this, to an extent, with the stereotype concept, but I don't know that it gets very far (or, at least, it hasn't to date). Gregory Woodhouse [EMAIL PROTECTED] "Judge a man by his questions not  his answers."   --Voltaire

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