[mapserver-dev] MS-RFC-123: Support for MapML output in MapServer
Even Rouault
even.rouault at spatialys.com
Thu Mar 12 06:12:21 PDT 2020
Hi Daniel,
> https://mapserver.org/development/rfc/ms-rfc-123.html
Regarding REQUEST=GetMapML, the RFC mentions that this is an extended request
of the WMS service. But none of the examples/text where it is used have
SERVICE=WMS parameter. I guess this is needed.
I was wondering if the Vendor-specific GetMapML Request was a MapServer
specific thing of a MapML thing. According to
https://docs.ogc.org/per/17-019.html (if that doc is still current), it might
be a more generic MapML thing. But the parameters for the request they give
there in table 4 and 5 seem a bit different than the one you suggest.
Grepping getmapml through GeoServer code base doesn't show any occurence
https://github.com/geoserver/geoserver/search?q=getmapml
whereas looking just for mapml does. Hence my confusion.
And it seems that Cubewerx has implemented a GetMapML request as part of WMTS
(not WMS): there's a Operation name="GetMapML" in the output of
https://demo.cubewerx.com/cubewerx/cubeserv/simple?
SERVICE=WMTS&REQUEST=GetCapabilities
Wondering if there's something in the GetCapabilities of WMS planned to
advertize the availability of the GetMapML request ? (if that's possible to
extend the response of GetCapabilities in a standard compliant way)
==> Answering to myself, https://docs.ogc.org/per/17-019.html mentions
"If this proposal is accepted by the MapML community as a service that
generates MapML files, it will be necessary to consider what concrete changes
are needed to be done in the GetCapabilities response to expose the
possibility of having GetMapML requests"
Regarding "The text/mapml feature collection output format in response to WMS
GetFeatureinfo and WFS GetFeature requests will be generated via a new OGR
<mapml> output driver.", if that's the route actually followed, perhaps the
RFC should mention clearly (in "4. Limitations / caveats", or in a
"Requirements" paragraph) that this part will be dependent on running
Mapserver against a GDAL version with that driver.
I guess an alternative could be to leverage the MapServer template mechanism
to drive the generation of the <mapml> element (but I'm not an expert of this,
although I think it can do quite powerful things)
Regarding -DWITH_MAPML=1 switch, I was wondering if making it available
unconditionally (or at least with the same conditions of WITH_WMS / WITH_WFS)
wouldn't make things simpler. Additional build switches increase the number of
configurations that should potentially be tested, and we generally only test
one in CI, and as what is not tested should be assumed to be broken unless
otherwise proven (as was found with non-GDAL and non-PROJ build)... :-) But
this is a minor point.
I assume msautotest will be extended to trigger the new code paths ?
Even
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http://www.spatialys.com
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