[xquery-talk] Top N Most Common Mistakes

rpbourret at rpbourret.com rpbourret at rpbourret.com
Mon Aug 13 12:24:02 PDT 2007

On Mon, 13 Aug 2007 13:11:43 -0500, Smith, Donald T. wrote
> Ron,
> Curious if the schemas you are facing are mostly machine generated (that
> is, from some IDE) or if they are hand-crafted. And if hand-crafted, 
> do they show any discernable design patterns (by which I mean XML Schema
> design patterns). Do any of these issues make the schemas easier or
> harder to learn?
> Don

As far as I know, they're hand generated, based on some ISO specs in the
geographic world. I've had two major problems:

1) Learning the subject matter itself (geographic metadata)

2) Working with extremely generic XML of the style:

   <Parameter Name="foo">

   It's actually much worse than that, with parameters allowing a choice of
stuff instead of just values. There are a fair number of co-constraints (i.e.
if the parameter is of this type, we always use this form of parameter) but
these aren't documented anywhere.

There are also a number of referential structures (i.e. take the value of this
element and go look up another element with an attribute having the same value).

I wouldn't say that the schemas are really all that complex, it's just the
usual learning curve of a consultant getting dumped into an unfamiliar
environment and being expected to know everything at once.

I think the interesting thing is that, when I finally figure out what the
actual query is and what the schema structures I want to work with are,
writing the XQuery query is almost trivial. No idea if this is a common
experience, but it does make me like using XQuery.

-- Ron

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