NYCPHP Meetup

[Elliotte Harold]

bz-gmort at beezifies.com wrote:

> What you seem to be saying here is "I can add a record type whenever I 
> need it and call it whatever I want".
> 
> So in a hospital, a doctor decides for some reason he needs to track toe 
> size of the patient over treatment.  So he adds in a toe-size tag
> <toe-size>3</toe-size>
> 
> And records that with every visit.
> 

Doctors wouldn't do that. (Well noted XML guru Jonathan Borden, M.D. 
might but most doctors wouldn't.) Instead they'd fill out a form just 
like they do today.

The difference is that when the form doesn't let them include the 
information they need, they can ask the devs to expand the form, and the 
devs can do that without breaking all their existing databases. if the 
devs are really good, they'll have figured out how to organize the forms 
to allow doctors to expand it without realizing that's what they're doing.

Certainly SQL databases can be evolved, but it's really hard to do. Read 
Refactoring Databases by Scott Ambler one of these days to see exactly 
how hard it is; but it is possible. Scott proved that. However when 
working on the book he was told repeatedly by data professionals that 
what he was proposing was impossible. he wrote the book to prove that it 
wasn't impossible, merely difficult.

In XML land, refactoring databases goes from merely possible to actively 
encouraged and expected.

-- 
Elliotte Rusty Harold  elharo at metalab.unc.edu
Java I/O 2nd Edition Just Published!
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