[Tilecache] WMS getMap interface

[Christopher Schmidt]

On Tue, Sep 15, 2009 at 04:39:00PM +0200, Simone Gadenz wrote:
> Hello!
> 
> I am looking for a WMS server that can consume a TC cache and provide images
> of an arbitrary extent.
> 
> According to the documentation each tile can be called using a WMS syntax.
> For the short test I have done there is no possibility of calling images
> with an arbitrary extent through that interface.
> 
> I found GDAL has a minidriver for accessing WMS-C caches but again for the
> test it seems it works only for accessing a single tile. I might be wrong
> since i did not understand fully the configuration.

This should work. Did you try one of the example configurations?

  http://gdal.org/frmt_wms_metacarta_wmsc.xml

As a RASTER type datasource in MapServer should let you request any WMS
extent and have it fill the data using the TileCache backend. (Oh, 
but that WMS service is down, so that doesn't really let you demonstrate;
but still, if you have an EPSG:4326 map, that file shoudl be easy to adapt).
I'll try and get that server back up later today or tomorrow morning.

> Going to the point, I would like to understand how hard would be to
> implement a WMS getmap interface into the TileCache, and in case what is the
> best strategy. I saw a WMS.py under the service folder. is thet the right
> point to start?

Possibly, but I am not in favor of adding image mosaicing to TileCache;
I think you would be best to try to get GDAL+MapServer working rather
than changing the way TileCache works in this way.

(There are, I believe, at least 3 different files called WMS.py.)

Changing this would require changing a significant amoutn of core
infrastructure of TileCache to accomodate for this use case.

REgards,
-- 
Christopher Schmidt
MetaCarta