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Re: maps

• To: xml-dev@l...
• Subject: Re: maps
• From: "Thomas B. Passin" <tpassin@c...>
• Date: Sun, 04 Aug 2002 13:07:55 -0400
• References: <4.2.0.58.20020804122008.02349610@p...>

[Simon St.Laurent]
[[
There's no type in WXS for locations.  I can't use the built-in types to
express something like:

<zoo>
   <name>Utica Zoo</name>
   <lat>75°15'00" N</lat>
   <long>43°05'00" W</long>
</zoo>

I can create a type with a regular expression constraining its lexical
appearance, but there's no value space, so I can't compare, for instance,
75°15'00" N with 75.2500° N.

I have similar problems created by the lack of any notion of units in W3C
XML Schema.  When I was looking at GPS devices, I found information that
the accuracy under the forest canopy was off by 7-21.  Mentally I read that
as feet (since I was in the US), but it was of course in meters.  Since the
particular maps I'm making are only 52 feet 8 inches in diameter, 23-67
feet off is kind of a problem.  I'm also creating software which will
hopefully be used in both US and metric environments, so an understanding
of units is crucial.  (For a kicker, I'm using compass coordinates, which
plot differently from polar coordinates.  How to explain that?)

 From one perspective, it seems like the right answer is to bang on the W3C
XML Schema Working Group's door and ask for new primitive types ...
]]

This is not really a good idea, because in addition to the reasons you give
below, there are many existing (non-XML) standards, each of which deals with
locations and lat-long in its own way.  There is no one way that XML Schema
could come up with that would be widely suitable.  This reinforces your main
point.

[[
which have
The biggest problem I have with strong typing is that most problems need
different types and particularly different understandings of value
spaces.  While programmers may be fooled into thinking that the set of
primitive types they use in their code is somehow magically blessed,
there's no such blessing once you step outside the world of programmers.
]]

Cheers,

Tom P

• References:
  • maps
    • From: "Simon St.Laurent" <simonstl@s...>

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