Re: XML for linguists?

On Thu, 18 Nov 1999, David G. Durand wrote:

>
> This is true, but if you have highly recursive structures in your XML (like
> nesting clauses) relational representations are provably inferior, since
> they cannot easily express notions like "ancestor" or "descendant." In
> particular, the various ways that these notions can be expressed are either
> difficult or impossible to edit efficiently, or are difficult to query.
>
> Some academic projects have extended relational theory with appropriate
> fixed-point operators in their query languages, but this is definitely
> still research, not common practice.
>
Oracle has a few extensions to SQL that let one work with tree-like
structures. I even used them once, but they are hard to use. Currently,
I have a recursive table:

create table lng_element(
elementnr number(10) not null
parent_elementnr number(10) not null
...);

which means I can nest as deep as I want. I gather the whole tree into
and XML document, which can be edited, and then unrolled into the
database. The user interface is a bit trickier, but what's a few bugs
amongst friends? They'll get ironed out in due time.

> My experience is that it's not too hard to represent the surface structure
> of an XML document in a database, or of a database in an XML document, but
> that they offer rather different data models and processing possiblities.
> Of course, hybrid approaches are often the best, as relational engines are
> often good at flexibly representing linking structures, while XML is better
> at representing the static structure of a single document or piece of
> information.
>
Yes, I've been quite amazed at the ease with which it is possible to
fool around with XML representations of data. (By the way, don't go
looking in the current release of Kura for the XML bits, they're not
in it yet.)

> When XLink finally issues, I expect people to start building interesting
> systems based on structured text in XML using XML tools, combined with
> relational engines to handle much (but not all) of the heavy lifting of
> link management.
I'm as ignorant as Dr. Livingstone returning from the jungle - what's
XLink?

>
> The public parts of the W3C's XML archives have some good discussion of
> this point, around the issue of whether attributes should have been
> included in XML at all.
>
It's good to know I'm not the only one to have this problem...

Boudewijn Rempt  | http://denden.conlang.org