xml-dev - OK, I've read some books, tons of articles, and...

[moliphan@footprint.com]

I am still having a bit of trouble understanding the potential applications
of XML. Perhaps a reader would be good enough to confirm whether my
thoughts, expressed below, are valid.

By creating an XML file and a DTD, you have a defined, portable set of
business rules - portable, because if I send you my XML file which contains
a reference to a DTD I have created and which is located on the Internet,
you are presumably unable to alter the contents if I impose a validity
check.

The structure of XML allows parties interested in my data to do searches
with filters specific to the structure of the data. For example, knowing
that a "Grommet" element exists with a "Magical" attribute, interested
parties could search for Grommets with a Magical attribute of "Yes". A
common storage area for DTDs would possibly allow those unfamiliar with my
data structure to view it.

As the data is using an "Open" definition, it is available to a wider
audience. Perhaps it can be processed in more than one manner in one
session. My idea here is: perhaps I am viewing information a product and
decide to order it. My act of placing an order performs some processing on
the vendor's behalf, and potentially on mine as well.

A question I have is, how does my behaviour travel with the data (as
structure does not define behaviour)? I have seen how Java parsers can
traverse document elements, and given elements I can now associate actions
with them using Java, but how does that help you, my interested party
unless you can use my code with the data?

Also, is an XML file going to act as a database in some circumstances?
Although I have seen examples of this, I wonder how the heck that is
supposed to work with the portability idea as multiple database instances
would be difficult to reconcile.

The paradox as I see it is that XML provides an open definition of
structuring data, but there is difficulty then in providing a generic (low
cost) method of using the data. My data will be (and, hopefully act)
different from yours and everybody else's, therefore no generic agent is
going to know what to do with it.

Thanks in advance.

Mike Oliphant



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