XSL & Stuff
Joel Meulenberg
joelmeulenberg at yahoo.com
Fri Sep 21 00:58:44 CDT 2001
Wow! I didn't expect such a flurry of comments to come out of the
questions I asked. I was actually more interested in your
opinions/experience with using "trees" (strictly hierarchical structure
which allows only 1-to-many relationships between entities) as the
fundamental model for your data as opposed to using relations as the
fundamental model for your data.
I'll ask a couple more questions about that below...
> >What do you mean by an "XML database"?
>
> Here's the deal. Use a nifty, propietary way to store
> data in a compact format. Create a process to turn a
> single item (product, set of products, whatever) into into
> XML using MS Tools. This is done on-demand, so
> we don't need to store the data in XML format.
>
> Use XSL to transform that XML into HTML.
>
> This allows us to separate the data storage layer (proprietary)
> from the business logic (make XML) from the presentation
> layer ("Stock" HTML pages that are filled dynamically).
>
> If you think about it, you can create several different XSL
> "templates",
> and apply a different Template to get a different view of the data.
I dig. Using XSLT to "repurpose" the data, etc. (Two transformations
seems a little heavy, but I'm sure it's not that big of a deal.)
I'm wondering how the "make XML" step embodies "business logic"?
I'm also wondering how one would query the proprietary data store?
> >If it's more like a data file, then I'm curious about your
> >opinions/experiences with storing the data in independent
> hierarchical
> >data structures (i.e.- the XML documents)
>
> Too much disk space.
>
> >in contrast to storing data in relations (tables) in a DBMS?
>
> Too much disk space.
> And too expensive. (Or hard to maintain, if you're an open-sourcer)
> And takes too many clock cycles.
I'm not so interested in physical storage aspects, etc. I'm more
interested in how you like working with a hierarchical model of data as
opposed to a relational model of data. *Both* hierarchical databases
and a relational databases (in the abstract sense - I'm not referring
to any particular SQL product (none of which are quite relational
anyway)) *can* be stored compactly and can perform well given the right
implementation.
(Indeed some of the followup comments of others suggest that has been
their experience.)
It's your feelings/experiences with the fundamental abstractions (i.e.-
tree versus relation) that I'm wondering about.
The shortcomings of always trying to shoehorn data into a strictly
hierarchical structure were recognized decades ago and that's why the
idea of hierarchical databases was essentially abandoned in the 1980's.
(e.g.- The hacks that people had to use to handle a many-to-many
relationship in a model of data that only allowed one-to-many
relationships were horrible.)
Have you felt any "impedance mismatch" between your data and the
strictly hierarchical structure imposed by XML?
I could ramble some more, but I've been told my emails get too long and
then no one wants to read them, so I'll stop here. : )
Thanks for the clarification so far.
+Joel
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