12. Sächsisches GIS-Forum Dresden: 18./19.05.2012 GI2012-OpenDataPolicies-FORUM

1. Implementing of OGC and INSPIRE Standards
From Theory to Reality
Jáchym Čepický, Štěpán Kafka
&
Tomáš Mildorf, Michal Šrédl, Přemysl Wohnout
19.05.2012 HSRS & CCSS 1
GI2012

2. System overview
Technology behind the CCSS Geoportal
WMS
WMS-T
Web Client Server proxy WFS, FES OWS Servers
WCS
WMS++ ...
HSLayers Proxy4ows  MapServer
(JavaScript) (Python)  GeoServer
 InterGraph
- OpenLayers - Mapserver / MapScript  ArcGis
- Ext - Gdal / Ogr
- OwsLib
19.05.2012 HSRS & CCSS 2
GI2012

3. Mission
Challanges & Results
 Display huge WFS data in web client → Proxy4ows
 Filter Encoding (FES) → OpenLayers, OwsLib, MapServer patches
 WFS Axis order issue → MapServer, OwsLib patches
→ some issues still remain
19.05.2012 HSRS & CCSS 3
GI2012

4. Proxy4ows
 Transforms WFS and WCS to WMS
 For WMS, it transforms the coordinate systems
 [ http://proxy4ows.org ]
 Will be presented in Prague
19.05.2012 HSRS & CCSS 4
GI2012

5. Filter Encoding
OpenLayers – <Filter_Capabilities> not parsed
Part of a WFS 1.1.0 GetCapabilities response
19.05.2012 HSRS & CCSS 5
GI2012

6. Filter Encoding
OpenLayers – <Filter_Capabilities> not parsed
Desired result
Patch proposed
- Comparison filters & related stuff
- WFS 1.0.0 and 1.1.0
19.05.2012 HSRS & CCSS 6
GI2012

7. Filter Encoding
MapServer – Filter produced as invalid XML
"wfs_filter" '<ogc:PropertyIsEqualTo xmlns:ogc="http://www.opengis.net/ogc">
<ogc:PropertyName>STUPEN</ogc:PropertyName> <ogc:Literal>3</ogc:Literal>
</ogc:PropertyIsEqualTo>' Mapfile
Mapserver code
FILTER=<ogc:Filter>
<ogc:PropertyIsEqualTo+xmlns:ogc="http://www.opengis.net/ogc">
<ogc:PropertyName>STUPEN</ogc:PropertyName>
<ogc:Literal>3</ogc:Literal> Outgoing filter
</ogc:PropertyIsEqualTo>
</ogc:Filter>
19.05.2012 HSRS & CCSS 7
GI2012

8. Filter Encoding
MapServer – Filter produced as invalid XML
"wfs_filter" '<ogc:Filter xmlns:ogc="http://www.opengis.net/ogc">
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>STUPEN</ogc:PropertyName> <ogc:Literal>3</ogc:Literal>
</ogc:PropertyIsEqualTo> </ogc:Filter>' Mapfile
One-char patch
FILTER=<ogc:Filter+xmlns:ogc="http://www.opengis.net/ogc">
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>STUPEN</ogc:PropertyName>
<ogc:Literal>3</ogc:Literal>
</ogc:PropertyIsEqualTo> Outgoing filter
</ogc:Filter>
19.05.2012 HSRS & CCSS 8
GI2012

9. WFS Axis Order
 WFS 1.0.0
 Axis order clearly defined in standard (East, North)
 <wfs:LatLongBoundingBox> causes confusion sometimes
 WFS 1.1.0
 As widely accepted, axis order should follow the definition of the
particular CRS
 However, not a strict requirement in the standard
 Implementations of standards differ, heaps of confusion
 Axis order depends not only on the CRS, but also on the notation used
19.05.2012 HSRS & CCSS 9
GI2012

10. WFS Axis Order
WFS 1.1.0
 Axis order depends on the SRS used
 Check http://www.epsg-registry.org/ for definitions
 BBOX url parameter
 Sometimes you need to negotiate with the service providers to
follow the definition, as otherwise no data may be returned
 Data themselves
 MapServer did not understand, that the axis order depends on
the SRS used, data was rotated by 90°
 MapServer patch provided
19.05.2012 HSRS & CCSS 10
GI2012

11. WFS Axis Order
WFS 1.1.0
Axis order depends on the notation of the SRS as well:
 EPSG:EPSG_code
→ WFS 1.0.0 style – fixed East, North
 urn:EPSG:geographicCRC:epsg_code
→ Follow-up the definition
 http://www.opengis.net/gml/srs/epsg.xml#EPSG_code
→ We don't know
19.05.2012 HSRS & CCSS 11
GI2012

12. WFS Axis Order
MapServer as WFS 1.1.0 Client
 More details here:
http://les-ejk.cz/2012/03/mapserver-as-wfs-1-1-0-client-not-suitable/
19.05.2012 HSRS & CCSS 12
GI2012

13. Patches available
OpenLayers – <Filter_Capabilities> not parsed
http://trac.osgeo.org/openlayers/ticket/3652
(Patch proposed)
MapServer – Filter produced as invalid XML
http://trac.osgeo.org/mapserver/ticket/4171
(Expected in 6.2)
MapServer – WFS Axis order
http://trac.osgeo.org/mapserver/ticket/4228
(Expected in 6.2)
OwsLib patches already deployed
19.05.2012 HSRS & CCSS 13
GI2012

14. Thank you!
Hope to see you in Prague:
19.05.2012 HSRS & CCSS 14
GI2012