[Mapserver-users] WFS client howto

[Daniel Morissette]

Gregor Mosheh wrote:
> 
> Our WMS system works A-OK, although the rasters are often reprojected by
> the client (we use DD for the datasets, LCC or a UTM is usually used for
> the output) and so they come out looking al funky. That's what we were
> really trying to avoid. Perhaps, if WFS won't work for these needs, a
> solution could be found with WMS?
> 

You could avoid reprojection on the client side by advertizing multiple 
projections in your server's capabilities.  You would do that by listing 
multiple EPSG codes in the wms_srs metadata on your server, either at 
the top level of the map, or in a specific layer.

e.g.

  METADATA
   "wms_srs" "EPSG:4326 EPSG:xxxxx EPSG:yyyy EPSG:zzzz"
  END

In WMS, a layer inherits the list of SRS of its parent(s), so it's 
enough to list all the supported SRS once at the top-level in the map.

Then if you use a smart WMS client it should do the right thing 
automatically and request the layer in the output projection if it's 
available, avoiding the raster reprojection. If you use MapServer as a 
WMS client and create the mapfile by hand then you should copy the 
wms_srs metadata to the client mapfile to tell MapServer which SRS are 
available on the remote WMS server. Then at map display time MapServer 
will try to find a matching projection in the list, and will default to 
EPSG:4326 only if it can't find a match.

HTH

Daniel
-- 
------------------------------------------------------------
  Daniel Morissette               dmorissette at dmsolutions.ca
  DM Solutions Group              http://www.dmsolutions.ca/
------------------------------------------------------------