Request:
http://localhost:9000?service=WFS&version=1.1.0&request=GetFeature&TypeName=places&outputformat=geojson&filter=<Filter xmlns="http://www.opengis.net/ogc">
<Intersects>
<PropertyName>geometry</PropertyName>
<Polygon xmlns="http://www.opengis.net/gml" srsName="EPSG:4326">
<exterior>
<LinearRing>
<posList>
-0.6389 42.5922
10.2683 51.9106
14.5196 41.0320
-0.6389 42.5922
</posList>
</LinearRing>
</exterior>
</Polygon>
</Intersects>
</Filter>