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

[Mike Champion <mcc@arbortext.com>]

At 05:01 PM 6/4/98 -0400, moliphan@footprint.com wrote:
>
>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?

I see two ways in which XML helps here:  First, the simple but powerful
syntax allows Perl-type scripts to relatively easily extract specific
content from the XML markup without having to "understand" anything about
the document itself.  Second, there *are* standard APIs emerging to allow
Java, C++, etc. programs to process a variety of XML data in a common way;
these include the "Simple Api for Xml" or SAX convention for interfacing to
parsers, and the forthcoming W3C "Document Object Model" or DOM API to
facilitate the kinds of things that "Dynamic HTML" scripts do, but for a
standard way across XML applications.  Between Java or JavaScript, XML and
these APIs, you can widely share code and data in a convenient way.  

>
>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.

XML-based "schemas" can make it easier to interchange data; think of it as
a generalized, somewhat self-describing data exchange format  rather than a
silver bullet to solve the portability problem.

>
>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.

There are a number of XML-based "metadata" initiatives, notably the
"Resource Definition Format" or RDF that provides a set of conventions by
which your data can be described, and this description interchanged with a
database schema.

It sounds to me like the "generic agent" you talk about would be a
full-blown "artificial intelligence" that's well beyond the state of the
art.  XML merely provides a syntax or meta-language, and a set of
conventions such as RDF, so that "artificial idiot-savant" applications or
SPECIALIZED agents can be defined and widely exchanged.  In other words,
it's a set of conventions that let's us move forward more quickly than we
have with HTML and a wide range of proprietary data formats, but it is by
no means a universal knowledge representation format that would take us a
quantum leap into the future.


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