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Hi Stan,<br>
<br>
As I have said before their is much merit in expressing some
biodiversity data in GML but not committing to do everything with it.
We would end up having to port whatever vocabularies we come across to
GML application schemas. <br>
<br>
There is also merit in expressing OGC 'stuff' that is of interest to us
as an RDF compatible vocabulary so that we can embed it in things that
are chiefly not about location. Some examples:<br>
<ul>
<li>If you call a LSID for a willow specimen the metadata for that
specimen will be in RDF and it may need to contain information about
how it has been georeferenced. The georeferencing concepts are probably
all OGC 'objects' but expressed as RDF. You don't want to have to
understand GML just because you are handling data that is OGC
compliant. Your interest may be in sequencing the specimen not mapping
it.</li>
<li>If you call for an analysis of distribution patterns among
200,000 willow specimens then you probably want to do it in a
geographic-centric way (possibly GML) and also express some basic
taxonomic info in there like their names.<br>
</li>
<li>If you want to get a description of the differences between
species of willow so you can link it to the gene expression work you
are doing in the lab you probably don't want it to have anything at all
to do with GML.</li>
</ul>
So it is "horses for courses" rather than GML with everything.<br>
<br>
Darwin Core is simple enough as a vocabulary that it will probably be
expressible in many forms.<br>
<br>
Does that make sense?<br>
<br>
Roger<br>
<br>
<br>
Blum, Stan wrote:
<blockquote
cite="mid91A8D99838A257439749E1AB777DED280FF724@yoshi.calacademy.org"
type="cite">
<meta http-equiv="Content-Type" content="text/html; ">
<div>I (we) desperately need to solve the puzzle of how to compose
(re-use) conceptual specifications. Can we create a flexible system of
base classes that can be snapped together to make useful data exchange
applications? I think this is one of, if not THE most import tasks for
the incipient TDWG Architecture group.</div>
<div> </div>
<div>So I'm trying to educate myself about RDF versus XML (and their
respective schema tools). I came across this comment on RDF versus
GML, <a href="http://www.mapbureau.com/gml/">http://www.mapbureau.com/gml/</a>,
which contained this:</div>
<div>
<p><font color="#ff0000"><excerpt></font><br>
[...] GML is not directly composable with other XML languages. Entities
that are described by other languages cannot legally play the role of
geographic features in GML. This because all types of geographic
features are required to derive from the GML abstract class <b>gml:AbstractFeatureType</b>.
Even if it were not for this formal requirement, the lack of
conventions about how to represent even simple semantic notions in XML
languages would prevent effective integration of GML with XML languages
developed independently. </p>
<p>The non-composability of GML requires that it absorb as
application schemas the multitude of other domains to which
geographical information is relevant. Failing this, non-standard
mechanisms of some kind must be used to relate GML content with
external data.</p>
<p>Indeed, GML positions itself as a universal, rather than
geography-specific, semantic standard by including its own general
formalisms for collections, assertion of properties (in a style very
much like RDF), time and processes, and reference between content in
separate files (via Xlink). GML can be viewed as an alternative not
just to geography in RDF, but to RDF itself. <br>
<font color="#ff0000"></excerpt></font></p>
<p>This seems like a problem for us because some aspects of our
biodiversity information are decidedly not spatial. Is this a problem
with XML Schema generally or just the way it was used to create GML?
Several TDWGers are getting enthusiastic about RDF, despite the
cautions of McCool (referenced by Bob Morris earlier on the TDWG-GUID
list). Should we go ahead and cast DarwinCore as a GML application
while we gear up for a coordinated switch to RDF?</p>
<p>-Stan</p>
</div>
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<br>
<br>
<pre class="moz-signature" cols="72">--
-------------------------------------
Roger Hyam
Technical Architect
Taxonomic Databases Working Group
-------------------------------------
<a class="moz-txt-link-freetext" href="http://www.tdwg.org">http://www.tdwg.org</a>
<a class="moz-txt-link-abbreviated" href="mailto:roger@tdwg.org">roger@tdwg.org</a>
+44 1578 722782
-------------------------------------
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