[mapserver-users] MapServer seems to always use GDAL driver with cascaded WMS (instead of AGG)

["SAEZ Laurent - CETE Méditerr./DI/ETER"]

Hi,

I have some troubles using AGG with cascaded WMS.
I have my first mapfile that exposes WMS layers (MapServer is used as a 
WMS server and a WMS client ) : refs.map
I have a second mapfile that contains a Postgis layer (this mapfile uses 
only MapServer as WMS server) : roads.map
I'm using MapServer 5.6.3 with patch r9635 on Debian (to advertise my 
desired "GetMap formats" in the WMS/Capabilities) .
I can get nice PNG with AGG when I request directly my second mapfile 
routier.map (using mapserver only as WMS server).
But if I request my first mapfile (that then requests my second mapfile 
using MapServer as WMS client), I get PNG with bad aliasing (AGG does 
not seem to be used!).

I looked at the mapserv.log (for the WMS/GetMap that requests the 
cascaded WMS) and I saw : "msDrawGDAL(): red,green,blue,alpha bands = 
1,2,3,4"
Does "msDrawGDAL" meen that DGAL driver is used instead of AGG driver ?

Thanks for your reply.
Laurent
NB : Sorry for my poor English...

An excerpt from my first mapfile (refs.map):
"MAP
...
    OUTPUTFORMAT
      NAME "PNG"
      DRIVER "AGG/PNG"
      MIMETYPE "image/png"
      IMAGEMODE RGBA
      TRANSPARENT ON
    END
    ...
    WEB
      ...
      METADATA
         ...
         "wms_getmap_formatlist" "image/png,image/jpg,image/jpeg"
      END
    END
    LAYER
      NAME "my_layer"
      ...
      CONNECTIONTYPE WMS
      "http://my_domain/cgi-bin/mapserv?map=/my_path/roads.map"
      METADATA
        WMS_NAME "my_roads"
        "wms_server_version"  "1.1.1"
        "wms_format" "image/png"
        ...
      END
    END
    ...
END"


An excerpt from my second mapfile (roads.map) :
MAP
...
    OUTPUTFORMAT
      NAME "PNG"
      DRIVER "AGG/PNG"
      MIMETYPE "image/png"
      IMAGEMODE RGBA
      TRANSPARENT ON
    END
    ...
    WEB
      ...
      METADATA
         ...
         "wms_getmap_formatlist" "image/png"
      END
    END
    LAYER
      NAME "my_roads"
      ...
      CONNECTIONTYPE    postgis
    ...
    END
...
END