[Qgis-developer] WFS question in QGIS master

[Even Rouault]

Hi Andreas,

> 
> Is this a problem in the WFS server or in the client issueing an invalid
> request? Can QGIS do something do be more tolerant and display this WFS
> layer?

There are several issues :

- the server doesn't like srsname of the form urn:ogc:def:crs:EPSG::XXXXX, but 
only EPSG:XXXXX. This is a bit a mix of the fault of the client & server here. 
The client does some internal normalization of the srsname when parsing the 
capabilities to store them in the form EPSG:XXXXX so that QGIS projection 
selector like them. And when issuing WFS requests, for WFS 1.0, it keeps 
EPSG:XXXXX and for later versions it uses  urn:ogc:def:crs:EPSG::XXXXX which 
is supposed to be the "new" way of specifying them (one could expect the 
server to return urn:ogc:def:crs:EPSG::XXXXX in WFS 2.0). Here it seems the 
Intergraph server doesn't like at all the new way. Some robustness could be 
added in the client to retry with the alternate way (and probably first try 
with the variant that was given in the capabilities)

- the schema returned by 
http://webdienste.zugmap.ch/landwirtschaft_naturschutz_wfs/service.svc/get?request=describefeaturetype&service=wfs&typename=gmgml:LW_Bewirtschaftungseinheiten&version=2.0.0 
is a bit too complex for the QGIS client and so it doesn't understand that 
"gmgml:Polygon_Surface_MultiSurface_CompositeSurfacePropertyType" is a 
geometry field (hence a geometry less layer reported). That could potentially 
be improved to hard code that this type is a polygon geometry (I see it is 
done in OGR GML driver)

- the response to GetFeature returned by 
http://webdienste.zugmap.ch/landwirtschaft_naturschutz_wfs/service.svc/get?SERVICE=WFS&REQUEST=GetFeature&VERSION=2.0.0&TYPENAMES=gmgml:LW_Bewirtschaftungseinheiten&SRSNAME=EPSG:21781&COUNT=1
is not conformant with the WFS 2.0 spec. It should be a wfs:FeatureCollection 
and not a GML feature collection as in WFS 1.1. The QGIS client is robust 
enough to handle that however... But this is clearly a non conformance to the 
spec

- in the geometries returned, there are constructs like gml:CompositeSurface 
and gml:Arc that the QGIS GML importer will not handle. Falling back to the 
OGR GML services to parse them could potentially be done as it is able to 
handle them (just tried with 'ogrinfo 
"WFS:http://webdienste.zugmap.ch/landwirtschaft_naturschutz_wfs/service.svc/get" 
-ro --debug on gmgml:LW_Bewirtschaftungseinheiten -al -q' )

Even

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