[gdal-dev] Re: Ogr2ogr, WFS 1.1.0, -spat and gml:Box

Jukka Rahkonen jukka.rahkonen at mmmtike.fi
Mon Jan 9 05:12:51 EST 2012

Even Rouault <even.rouault <at> mines-paris.org> writes:

> > So it is WFS 1.1.0 request with the BBOX filter. But is it OK to give BBOX
> > as GML2 gml:Box if the service is WFS version 1.1.0? I have been thinking
> > it should be using GML3 and gml:Envelope instead.
> I suppose you're right. I didn't recall all the details, so I had a look at 
> the code, and here's the answer :
>     /* This is a heuristic to detect Deegree 3 servers, such as */
>     /* http://deegree3-demo.deegree.org:80/deegree-utah-demo/services */
>     /* that are very GML3 strict, and don't like <gml:Box> in a <Filter><BBOX> 
> */
>     /* request, but requires instead <gml:Envelope>, but some servers (such as 
> MapServer) */
>     /* don't like <gml:Envelope> so we are obliged to detect the kind of 
> server */
> So basically it seems that most servers are tolerant and will accept gml:Box. 
> But some servers that should accept gml:Envelope don't. So the default 
> behaviour is to use gml:Box, except in cases where we know it won't be 
> accepted (but the server mentionned in the comment is no longer online, and I 
> cannot find another one that doesn't accept <gml:Box>)
> It would perhaps be more reasonable to implement the reversed logic from a 
> theoretical point of view, but unless you can point me to a server that 
> doesn't like the current logic, I'm quite hesitant to change that 


The deegree3 demos can be found here http://demo.deegree.org/ and the Utah demo
seems to be at http://deegree3-demo.deegree.org:80/utah-workspace/services
I had a quick test and it did not complain about using <gml:Box> in <Filter>.
The result looks like correct, too.  So perhaps we can conclude that using
<gml:Box> with WFS 1.1.0 filters is probably wrong but because it works then it
will not be fixed.

I do not really like this ambiguous behaviour, though. Now for example WFS 1.1.0
bounding box guery with GDAL and EPSG:4236 leads to a mixture of using GML2
<gml:Box> that does not exist in GML3 but with a GML3 style Northing-Easting
coordinate order. However, normal GDAL user does not ever see it without
sniffing the web traffic and there is really nothing new with WFS being ambiguos
so perhaps I just need to take everything that is added to the stew and try to
remember all the tricks and pecularities while waiting for some comfortable
vector delivery service to appear.

-Jukka Rahkonen-

-Jukka Rahkonen-

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