<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
<title></title>
</head>
<body bgcolor="#ffffff" text="#000000">
Nick,<br>
<br>
We are very off topic for a postgis-users list, but I'll proceed until
warned away.<br>
<br>
There are two perspectives to your question:<br>
How does a temporal + spatial query get asked of a metadata
repository<br>
How does a metadata repository owner support temporal + spatial
queries<br>
<br>
This answer will generate more questions than answers, as there exists
no single best practice<br>
but instead a global mishmash of practices that can be cobbled together.<br>
<br>
<<attempting to be software independent>><br>
Government Information Location Service (GILS) (<a class="moz-txt-link-freetext" href="http://www.gils.net">http://www.gils.net</a>)<br>
a network of cross linked metadata repositories, geospatial and
othewise.<br>
<br>
Z39.50 (<a class="moz-txt-link-freetext" href="http://www.loc.gov/z3950/agency">http://www.loc.gov/z3950/agency</a>)<br>
A query protocol supported by GILS members<br>
<br>
A resource to z39.50 servers<br>
<a class="moz-txt-link-freetext" href="http://targettest.indexdata.com/">http://targettest.indexdata.com/</a><br>
<br>
BIB-1 (<a class="moz-txt-link-freetext" href="http://www.loc.gov/z3950/agency/defns/bib1.html">http://www.loc.gov/z3950/agency/defns/bib1.html</a>)<br>
geonetwork support the following BIB-1 attributes <br>
1-63, 1000-1028, 1030-1036<br>
<br>
using attributes 1118,1119,1120,1121 <br>
one could pose a spatial (bounding box) query<br>
<br>
using attributes 1125,1126,1127,1128,1129<br>
one could pose a temporal query<br>
<br>
using both sets one could pose a temporal + spatial query, if the
target z39.50 server supports it (Geonetwork does)<br>
<br>
<b><br>
</b><br>
------------------------------------<br>
On the server side<br>
One would need a separate metadata record for the data available for
each temporal + spatial result returned<br>
Otherwise a smart person could build a special modules with
(<a class="moz-txt-link-freetext" href="http://www.indexdata.dk/simpleserver/">http://www.indexdata.dk/simpleserver/</a>)<br>
to dynamically build temporallyl similar metadata records<br>
<br>
Otherwise you would be advertising data that is not accessible<br>
<br>
<br>
For a good start for a z39.50 server look to yaz
(<a class="moz-txt-link-freetext" href="http://www.indexdata.dk/yaz/">http://www.indexdata.dk/yaz/</a>)<br>
custom clients could use (<b><a class="moz-txt-link-freetext" href="http://perl.z3950.org/">http://perl.z3950.org/</a>)<br>
<br>
examples are given as starting points not as the only choices available/<br>
<br>
</b>C.<br>
<br>
<br>
<br>
Nick Bower wrote:
<blockquote cite="mid200612190358.49015.nick@nickbower.com" type="cite">
<blockquote type="cite">
<pre wrap="">IMHO Metadata and datastores are or should be separate functions.
Datastores provide access to vertices, Linestrings, Polygons, Raster
data, ....
Metadata servers provides a single, searchable repository to the
datastores avaliable at a location or enterprise.
....
Geonetwork stores metadata records as a BLOB in the database. That
means the entire XML document of a metadata entry is stored in a single
field.
You can very easily use XSLT functions in Postgresql or in any client
application to transform your metadata into any of the various formats
that are useful to you.
</pre>
</blockquote>
<pre wrap=""><!---->
How do combined spatial + metadata searches work in this case? Sequentially
with temporary tables maybe?
_______________________________________________
postgis-users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:postgis-users@postgis.refractions.net">postgis-users@postgis.refractions.net</a>
<a class="moz-txt-link-freetext" href="http://postgis.refractions.net/mailman/listinfo/postgis-users">http://postgis.refractions.net/mailman/listinfo/postgis-users</a>
</pre>
</blockquote>
<br>
</body>
</html>