We use Mapserver to create a composite of multiple layers from another WMS server. We noticed that a single request to Mapserver creates multiple requests to the "upstream" WMS server. Apparently Mapserver uses smaller tiles (that are based on the layer "SizeX" and "SizeY" config) instead of using the request bounding box it received.
E.g. incoming request to Mapserver:
And what Mapserver requests from the upstream WMS server (4 tiles):
Is there a way to disable this behavior in Mapcache? It should just use whatever bbox and resolution it got in its request for the upstream query.
We are using Mapserver 6.4.1-3~precise2 on Ubuntu but will upgrade fairly soon.
Our Mapserver config of the layer in question:
CONNECTIONTYPE UVRASTER
DATA "<GDAL_WMS>
<Service name=\"WMS\">
<Version>1.1.1</Version>
<ServerUrl>http://host/wms?&TIME=%TIME%&PROJECTION=%2Binit%3Depsg%3A3857&ENCODER=ENC1&</ServerUrl>
<SRS>EPSG:3857</SRS>
<ImageFormat>image/png</ImageFormat>
<Transparent>TRUE</Transparent>
<Layers>L1</Layers>
</Service>
<DataWindow>
<UpperLeftX>-20037508.34</UpperLeftX>
<UpperLeftY>20037508.340</UpperLeftY>
<LowerRightX>20037508.34</LowerRightX>
<LowerRightY>-20037508.34</LowerRightY>
<SizeX>40075</SizeX>
<SizeY>40075</SizeY>
</DataWindow>
<BlockSizeX>256</BlockSizeX>
<BlockSizeY>256</BlockSizeY>
<Projection>EPSG:3857</Projection>
<BandsCount>4</BandsCount>
<DataType>Byte</DataType>
<MaxConnections>4</MaxConnections>
<OverviewCount>10</OverviewCount>
</GDAL_WMS>"