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

[SAEZ Laurent - SG/SPSSI/CPII/DOM/ETER/PNE IG]

Hi,

I have some troubles using AGG with cascaded WMS.

I have my first mapfile that exposes WMS layers (MapServer 
<http://trac.osgeo.org/mapserver/wiki/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 <http://trac.osgeo.org/mapserver/wiki/MapServer> as WMS 
server): roads.map
I'm using MapServer <http://trac.osgeo.org/mapserver/wiki/MapServer> 
5.6.0 beta 3 on Debian (to avoid WFS requests issues with the following 
versions cf. http://trac.osgeo.org/mapserver/ticket/4073).
I advertise raster formats with "wms_getmap_formatlist". I define 
image/png to use AGG driver.
I can get nice PNG with AGG when I request directly my second mapfile 
roads.map (using mapserver only as WMS server).
But if I request my first mapfile refs.map (that requests my second 
mapfile using MapServer <http://trac.osgeo.org/mapserver/wiki/MapServer> 
as WMS client. This is the WMS cascade), 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


An extract of 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 ...

An extract of 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,image/jpg,image/jpeg"
        END
    END
    LAYER
        NAME "my_roads" ... CONNECTIONTYPE postgis
        ...
    END

I'm not sure that this behavior should be different with mapserver 6.0...

NB: I've already post this message on Tue, 27 Apr 2010 in the mailing 
list, but no reply... ;-(

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