[CITE-Forum] wfs-1.1.0-Basic-GetFeature-tc200.2 request

Andreas Schmitz schmitz at lat-lon.de
Tue Feb 21 10:21:24 EST 2012


Baris Kazar wrote:

Hi,

> <?xml version="1.0" encoding="UTF-8"?>
> <!-- test case id: wfs-1.1.0-Basic-GetFeature-tc200.2 -->
> <wfs:GetFeature xmlns:wfs="http://www.opengis.net/wfs" version="1.1.0" service="WFS">
> <wfs:Query xmlns:sf="http://cite.opengeospatial.org/gmlsf"
>     typeName="sf:EntitéGénérique">
> <ogc:Filter xmlns:ogc="http://www.opengis.net/ogc" xmlns:gml="http://www.opengis.net/gml">
> <ogc:BBOX>
> <gml:Envelope srsName="urn:ogc:def:crs:EPSG::4326">
> <gml:lowerCorner>34 14</gml:lowerCorner>
> <gml:upperCorner>41 23</gml:upperCorner>
> </gml:Envelope>
> </ogc:BBOX>
> </ogc:Filter>
> </wfs:Query>
> </wfs:GetFeature>
>
> For this request, there is one spatial column for the EntitéGénérique table.
> This request is missing <ogc:PropertyName> element which is normally
> set before the geometry element (ie, would have been before gml:Envelope element in this request).
> Therefore, it is obvious that the BBOX will be run against the single spatial column in EntitéGénérique table.
>
> What spatial column should be chosen for the other featureTypes whose tables have more than 1 spatial column?
> For instance PrimitiveGeoFeature has more than 1 spatial column.
> Should an exception be raised in that case because it is not apparent against which spatial column the
> BBOX is gonna run?

from the filter encoding spec, page 11:

The <BBOX> element is defined as a convenient and more compact way of encoding the
very common bounding box constraint based on the gml:Envelope geometry. It is
equivalent to the spatial operation <Not><Disjoint> ... </Disjoint></Not> meaning that
the <BBOX> operator should identify all geometries that spatially interact with the box.
If the optional <propertyName> element is not specified, the calling service must
determine which spatial property is the spatial key and apply the BBOX operator
accordingly. For feature types that has a single spatial property, this is a trivial matter.
For feature types that have multiple spatial properties, the calling service either knows
which spatial property is the spatial key or the calling service generates an exception
indicating that the feature contains multiple spatial properties and the <propertyName>
element must be specified. Of course a client application always has the options of
avoiding the exceptions by calling the DescribeFeatureType operation to get a
description of the feature type.

So for this test the service is required to figure out the appropriate
property by itself.

Best regards,
Andreas
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