[XML4LIB] re: databases or xml

Walter Lewis lewisw at hhpl.on.ca
Thu Feb 7 16:00:15 EST 2002


Stirnaman, Jason wrote:

> I'm just a newbie, but heregoes:  Is it correct to say that xml and
> databases should not be mutually exclusive?  As others have pointed out, the
> wonderous thing about XML is that it allows the creator/publisher/keeper of
> a document/content to give structure to that content.  The information about
> that content is now inseparable from the content itself and allows for it to
> be instantly communicable and translateable to any system and platform
> (wireless, MARC, relational database, web, etc).  Relational databases still
> have their place, but they can never provide for the sharing of information
> the way XML and other markup languages do.


Relational databases have an extraordinarily valuable role still, and 
its one that's worth keeping in mind -- along with the essay that was 
noted in the first reply to this thread.

RDBMS's are fast, well tuned, mature applications that perform very well 
on simply two dimensional data.  It doesn't take a master's degree to 
find ways to reduce a lot of content to "related" two dimensional tables 
and we're off.

One of XML's roles is shuffling data between disparate RDBMSs and it can 
replicate the structure in a way that is very transportable.

Many XML schema have much more in common with what one (or perhaps more) 
of what I understand a good object oriented database is designed to do 
-- deal with the messy issues of nesting inherent in many models of 
reality.

Spend a bit of quality time with the problems that the Text Encoding 
Initiative (http://www.tei-c.org/) is addressing. It's not uncommon in 
my work to see a nesting that runs:
	TEI.2/text/body/div1/div2/p/table/row/cell/name
The name index to this is exported to a SQL database (which one matters 
relatively little) and is used to dynamically create a URL which points 
to the ID values of the <div2> and the <p>.
	The same asp code that calls the database to build the links also manages 
the XSL transformations of the XML document.

If you want you see how that fits together at the end try:
	http://www.hhpl.on.ca/GreatLakes/
and follow the links to Hamilton Harbour or start at:
	http://edrh.rhpl.richmondhill.on.ca/


Walter Lewis

lewisw at hhpl.on.ca






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