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XML IN PRACTICE --- August 08 2002

How to Model a Bishop

By Sean Mc Grath

Way back in the Thirties, the linguist Benjamin Lee Whorf spent some time investigating the language of the Hopi Indians in Arizona. Hopi is a very interesting language that does not have a mechanism for distinguishing past, present, and future. This fascinated Whorf, who was interested in the degree to which the languages we speak affect the way we view the world.

To cut a long and utterly fascinating story very short, the Sapir-Whorf Hypothesis proposes that the language we use -- at least to some extent -- determines the way we view and think about the world around us.

Cut to the year 2002.

The place: A work cubicle near you.

The scene: Two developers fight over how best to model a piece of information.

Developer A: "It is obviously an element with a sub-element."
Developer B: "No, it is clearly a single element type with an attribute."

The Sapir-Whorf Hypothesis adds an interesting dimension to such debates that I first appreciated having read William Kent's excellent book "Data and Reality"[1]. I need to paraphrase Kent here as his book predates XML by a quarter of a century:

In XML, you are more likely to model a concept as an element rather than an attribute if the natural language you are working in has a noun for the concept.

Cut to some time in the near future.

The place: A work cubicle somewhere in Ireland.

The scene: A developer ponders an XML model of a Bishop.

The model that results from this modeling exercise depend on whether the developer thinks in Irish or English. Why? Because in the Irish language, a single word -- a noun -- means "back of the knee".

The word is "iscoid". Now before you ask, I do not have a 100,000 word Irish vocabulary! The reason I know this obscure word is that I remember a tongue twister I learned as a kid that goes like this:

Ta niscoid ar iscoid an Easpaig, agus ta imni ar an Easpaig faoin niscoid ata ar a iscoid.

Translated into English this says:

There is a boil on the back of the Bishop's knee. The Bishop is worried about the boil that is on the back of his knee.

So, a developer thinking in Irish is likely to model the back of a Bishop's knee as a sub-element of a knee element:

<iscoid>
...
</iscoid>

A developer thinking in English is likely to model it in terms of its position relative to the rest of the knee (or indeed the Bishop):

<knee position = "back">
...
</knee>

A lecturer of mine in College was fond of saying that Computer Science is basically mathematics with a bit of English thrown in. In a similar vein, XML modeling could be viewed as language with a bit of Computer Science thrown in.

Modeling aircraft must be a fun experience in Hopi as all things that fly share the same noun: "masa'ytaka".

Try handling that modeling problem without resorting to attributes!

NOTES

  1. 1stBooks Library, ISBN: 1585009709

 

Sean is co-founder and Chief Technology Officer of Propylon and is an industry–recognised XML expert.