An inquiry into the nature of XML and how it orients our perceptionof in

["Costello, Roger L." <costello@mitre.org>]

Hi Folks,

I oftentimes hear of people creating XML in an Object Oriented (OO) form, i.e., as classes and subclasses, or of people creating XML in a relational database form, i.e., as tables with rows and columns. I wonder if such forms are appropriate for XML? Does OO serve the same purpose as XML? Do relational tables serve the same purpose as XML?

Yesterday Philippe Poulard expressed a similar sentiment:

    I'm not sure that this OO paradigm can be applied 
    in XML: a class is defined by its unordered members that 
    a subclass can simply override, whereas the sequential 
    nature of XML doesn't allow overriding only a given part 
    of a content model.

    With ASL, I didn't try to adopt at any cost a feature that 
    doesn't fit well in XML technologies, I'd rather tried to 
    think different.

Lately I have been reading a couple of books [1][2] that have shaped my thinking on this subject. [1] asserts that the "form" in which information is expressed influences "what" can be expressed. Here are a few passages from the book:

    We experience the world through various lenses: speech, 
    the printed word, the television, and others.

    Each form classifies the world for us, sequences it, frames 
    it, enlarges it, reduces it, and colors it.

    The form in which ideas are expressed affects what those 
    ideas will be.

    Each form makes possible a unique mode of discourse by 
    providing a new orientation for thought and for expression.

In the computer information world there are various lenses: relational databases, XML documents, OO models, and others. Each form classifies, sequences, frames, reduces, enlarges, and colors our view of information. Each form orients our thought. 

If you accept that a relational/tabular form orients ones thinking a certain way and that OO orients ones thinking in another way, then it appropriate to inquire whether such forms are suitable for XML. Must not an XML document orient ones thinking in a way that is harmonious with the XML form? From [2]:

    The Parthenon did not serve the same purpose as its
    wooden ancestor.

    ...the structure of a building is the key to its beauty;
    ...new methods of construction demand new forms

What are the consequences of constructing XML documents as a collection of classes and subclasses, or as tabular rows and columns? Do we destroy the beauty of XML? Is the lens provided by XML distorted? XML orients our thought. In what ways?


/Roger

[1] "Amusing Ourselves to Death" by Neil Postman.
[2] "The Fountainhead" by Ayn Rand.