How do I propagate failures from upstream wms-servers?

[Trond Michelsen]

Hi.

In my mapfile, I have several layers with connectiontype WMS. Once in
a while, the WMS-servers that deliver these layers will fail, usually
due to high load, and return an application/vnd.ogc.se_xml
exception. In these cases, I'd like mapserver to return an exception
as well, but instead, mapserver will just log the error message in
MS_ERRORFILE, and continue drawing the rest of the layers. If there
are no more layers, it will result in a blank image.

(BTW: I've also noticed the same behaviour if the remote wms-server
answers with an internal server error)

Here's the layer definition that I use for testing. exception.cgi will
always return a dummy XML exception.

LAYER
    NAME "exception"
    TYPE RASTER
    STATUS ON
    CONNECTION "http://wms1.oslo.dnmi.no/cgi-bin/exception.cgi"
    CONNECTIONTYPE WMS
    OFFSITE 255 255 254
    METADATA
      "wms_srs"               "EPSG:4326"
      "wms_name"              "exception"
      "wms_server_version"    "1.1.1"
      "wms_formatlist"        "image/png"
      "wms_format"            "image/png"
      "wms_exceptions_format" "application/vnd.ogc.se_xml"
    END #metadata
END #layer

Is there something I can do to force mapserver to fail, and return an
exception if it fails to draw any of the wms-layers?

I'm using mapserver 4.10

$ cgi-bin/mapserv -v
MapServer version 4.10.0 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP OUTPUT=SVG SUPPORTS=PROJ SUPPORTS=FREETYPE SUPPORTS=WMS_SERVER SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT SUPPORTS=WCS_SERVER SUPPORTS=THREADS SUPPORTS=GEOS INPUT=EPPL7 INPUT=POSTGIS INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE DEBUG=MSDEBUG


-- 
Trond Michelsen