Code a web service with python/postgis

[lcelati at latitude-geosystems.com]

Dear all,

I would like code a web service with python. I have already imported  
several vector data
(land cover) and one Digital Elevation Model (raster layer) into my  
postgresql/postgis
database (server side).

I succeed in connecting to my pg db via psycopg2.

Client side, operators use a client application (Developed with PHP /  
javascript /
openlayers).

Objectives :  Client side, once the layer would be selected,and once  
the operators have
clicked on the map  , they would like that usefull informations appear  
on the interface
of the client application(kind of land cover, z of the DEM).


=> Regarding my python script, i have to type a SQL query in order to  
select usefull
informations of the db layers. And, of course, the information must   
depend on geographic
coordinates (Latitude Y/Longitute X).
In a 2nd time, my script must  produce a result(JSon type) for the  
client side.


It would be possible to help me regarding the coding in order to  
select usefull
informations of the db layers. (depends on geographic coordinates x/y   
? Could you throw
light for me regarding the way to do this SQL query ?

In advance, thank you to throw light for me.