Supporting mapml-proxy cascading

[dromagnoli]

PR supporting MapML proxy.

Checklist

• I have read the contribution guidelines.
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For core and extension modules:

• New unit tests have been added covering the changes.
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[prushforth]

I have successfully used this branch with the CFS CWFIS WMS (GeoServer!), and I found it works well in Remote request mode, except the remote GetFeatureInfo request balks at including of a blank cql_filter paramter:

e.g. the following template
https://cwfis.cfs.nrcan.gc.ca/geoserver/wms?request=GetFeatureInfo&query_layers=fdr_current&crs=EPSG:3978&bbox={xmin},{ymin},{xmax},{ymax}&language=en&cql_filter=&version=1.3.0&transparent=true&service=WMS&layers=fdr_current&width={w}&x={i}&feature_count=50&y={j}&styles=&info_format=text/html&height={h}

when filled out gives rise to an example query such as:

https://cwfis.cfs.nrcan.gc.ca/geoserver/wms?request=GetFeatureInfo&query_layers=fdr_current&crs=EPSG:3978&bbox=-1150222.572178498,-634225.7217853889,863260.6214545518,1688820.5909739062&language=en&cql_filter=&version=1.3.0&transparent=true&service=WMS&layers=fdr_current&width=761&x=381&feature_count=50&y=439&styles=&info_format=text/html&height=878

I find that if I edit the above URL and remove the cql_filter parameter entirely, it works ok:

https://cwfis.cfs.nrcan.gc.ca/geoserver/wms?request=GetFeatureInfo&query_layers=fdr_current&crs=EPSG:3978&bbox=-1150222.572178498,-634225.7217853889,863260.6214545518,1688820.5909739062&language=en&version=1.3.0&transparent=true&service=WMS&layers=fdr_current&width=761&x=381&feature_count=50&y=439&styles=&info_format=text/html&height=878

Maybe this is actually a bug in GeoServer cql_filter handling? Anyway, I will see if there are other cases I come across.

[dromagnoli]

PR updated with WMTS tests and getFeatureInfo with empty cql_filter being properly handled.

[prushforth]

Just returning to playing with this, and maybe it's something odd about the remote WMS, but I can't get it to proxy correctly, it always seems to truncate the "_en" from the remote URL. The remote WMS capabilities is here

The remote layer name to proxy is "WMS-Toporama", which is like a layer group afaict on the remote wms.

The client proxy always comes back with a 404, because it uses an incorrect URL in the tref attribute of the <map-link>:

Edit: Something similar seems to happen with this WMS - i.e. the base URL gets truncated and substituted with wms inadvertently.

[prushforth]

Ideally, creation (at all) of the <map-link rel="query"> would be conditional on if the remote layer is queryable.

IIRC GeoServer itself can cascade remote queries if the remote WMS supports some flavour of GML. Maybe we could change that when the Remote proxy option for MapML is selected, to text/mapml, text/html or text/plain availability? If none is available we would not create a <map-link rel="query" at all, as though the remote layer was not queryable in the first place.

[dromagnoli]

Ideally, creation (at all) of the would be conditional on if the remote layer is queryable.

IIRC GeoServer itself can cascade remote queries if the remote WMS supports some flavour of GML. Maybe we could change that when the Remote proxy option for MapML is selected, to text/mapml, text/html or text/plain availability? If none is available we would not create a <map-link rel="query" at all, as though the remote layer was not queryable in the first place.

I have updated the code so that it won't generate the query link if the remote server has none of these format supported.
I have also added a test.