Re: [xml-dev] more on "subelement significance"

[Bob Hutchison <hutch@xampl.com>]

On 01/10/03 4:20 PM, "Seairth Jacobs" <seairth@seairth.com> wrote:
> 
>  The usefulness of any given subelement is due to the knowledge of its
> namespace, document type, and/or parent element.  Without any of the three,
> the subelement does not have a useful meaning.
> 
> 
> Thoughts?

I'm with Simon on the convulsions. Here are a few thoughts that jiggled
loose. I'm not sure I've come to my senses yet, they seem a bit cluttered,
but here goes anyway :-)

XML is a data representation. What's the meaning of data? Does data contain
its own meaning?

There are people who will tell you that you cannot have meaning without a
mind. Do we want to go there? Maybe we do, because if this is true, then
there is nothing more to discuss.

What do 'usefulness' and 'meaning', even 'useful meaning' and 'useful
significance', have to do with each other anyway? They certainly are not the
same thing.

Are you talking about definition rather than meaning? I'm not sure you can
get definitions from what you have available in an XML document either
(except for the document itself).

It seems to me that your first sentence is kind of interesting. For the
parent to contribute to the meaning of the child, the parent must have
meaning... I think. Anyways, if it does, then it has to get it from its
namespace, document type, or parent. So we can substitute, and keep
substituting, and, with a bit of factoring, get: namespace, parent's
namespace, parent's parent's namespace, ..., or document type. So, we depend
on namespaces and a document type for meaning (possibly the root element if
we are desperate enough). I don't think this will do for meaning.

As an aside <html:a> tells you nothing more than <x:a> or even <a> -- you
need the namespace not the qualifier.

Here is a very common idiom (at least in my world):

    <things>
        <thing/>
        <thing/>
    </things>

<things> is used to keep <thing>s in one place to aid readability. What
meaning does thing get from things? What usefulness is provided to thing by
things? There is no namespace here, and I don't have to define a document
type. So there is no document type, namespace, or parental meaning in this
document. Yet I know that I can assign meaning as I like in the
interpretation of the XML (there's that mind thing again). Does the choice
of 'thing' for the element name matter? How? I think this last bit has to be
considered.

What if I showed you this XML document:

    <root>
        <things>
            <thing name="one"/>
            <thing name="two"/>
        </things>
        <people>
            <person name="Jack">
                <owns thing="one"/>
            </person>
            <person name="Jill">
                <owns thing="two"/>
            </person>
        </people>
    </root>

Where did the 'meaning' of <thing> happen for you? Did <things>, <root>, or
<people> contribute anything to your understanding? Did the use of English
words contribute anything? Consider:
    <a>
        <b>
            <d e='one'/>
            <d e='two'/>
        </b>
        <c>
            <h i='j'>
                <l m='one'/>
            </h>
            <h i='k'>
                <l m='two'/>
            </h>
        </c>
    </a>

This has the identical 'meaning' in XML as the previous example. It's just
that the human interpreter cannot interpret it very well.

What if I told you that I have been very successful when mapping XML
elements to objects (in Java) -- strictly one-to-one? In my world, an
element in XML maps to exactly one object, and each object to a single XML
element. What is the meaning of an object in Java? Or the usefulness of an
object in Java? Do objects obtain meaning from the things that refer them?
How much?

Why are you asking this question? I don't think I understand what you are
getting at.

Actually, I suspect a contributing cause, maybe the real cause, of Simon's
convulsions is the certainty that someone would post a message like this one
in response. Sorry :-)

Cheers,
Bob