[postgis-users] Metadata (fgdc, etc)?

[Carl Anderson]

Nick,

We are very off topic for a postgis-users list, but I'll proceed until 
warned away.

There are two perspectives to your question:
    How does a temporal + spatial query get asked of a metadata repository
    How does a metadata repository owner support temporal + spatial queries

This answer will generate more questions than answers, as there exists 
no single best practice
but instead a global mishmash of practices that can be cobbled together.

<<attempting to be software independent>>
Government Information Location Service (GILS) (http://www.gils.net)
a network of cross linked metadata repositories, geospatial and othewise.

Z39.50 (http://www.loc.gov/z3950/agency)
A query protocol supported by GILS members

A resource to z39.50 servers
http://targettest.indexdata.com/

BIB-1 (http://www.loc.gov/z3950/agency/defns/bib1.html)
geonetwork support the following BIB-1 attributes
1-63, 1000-1028, 1030-1036

using attributes 1118,1119,1120,1121
one could pose a spatial (bounding box) query

using attributes 1125,1126,1127,1128,1129
one could pose a temporal query

using both sets one could pose a temporal + spatial query, if the target 
z39.50 server supports it (Geonetwork does)

*
*
------------------------------------
On the server side
One would need a separate metadata record for the data available for 
each temporal + spatial result returned
Otherwise a smart person could build a special modules with 
(http://www.indexdata.dk/simpleserver/)
to dynamically build temporallyl similar metadata records

Otherwise you would be advertising data that is not accessible


For a good start for a z39.50 server look to yaz 
(http://www.indexdata.dk/yaz/)
custom clients could use (*http://perl.z3950.org/)

examples are given as starting points not as the only choices available/

*C.



Nick Bower wrote:
>> 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.
>>     
>
> How do combined spatial + metadata searches work in this case?  Sequentially 
> with temporary tables maybe?
>
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