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GI2012 sredl+team-implementing ows-v2

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

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GI2012 sredl+team-implementing ows-v2

  1. 1. Implementing of OGC and INSPIRE Standards From Theory to Reality Jáchym Čepický, Štěpán Kafka & Tomáš Mildorf, Michal Šrédl, Přemysl Wohnout19.05.2012 HSRS & CCSS 1 GI2012
  2. 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 - OwsLib19.05.2012 HSRS & CCSS 2 GI2012
  3. 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 remain19.05.2012 HSRS & CCSS 3 GI2012
  4. 4. Proxy4ows  Transforms WFS and WCS to WMS  For WMS, it transforms the coordinate systems  [ http://proxy4ows.org ]  Will be presented in Prague19.05.2012 HSRS & CCSS 4 GI2012
  5. 5. Filter Encoding OpenLayers – <Filter_Capabilities> not parsed Part of a WFS 1.1.0 GetCapabilities response19.05.2012 HSRS & CCSS 5 GI2012
  6. 6. Filter Encoding OpenLayers – <Filter_Capabilities> not parsed Desired result Patch proposed - Comparison filters & related stuff - WFS 1.0.0 and 1.1.019.05.2012 HSRS & CCSS 6 GI2012
  7. 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. 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. 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 used19.05.2012 HSRS & CCSS 9 GI2012
  10. 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 provided19.05.2012 HSRS & CCSS 10 GI2012
  11. 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 dont know19.05.2012 HSRS & CCSS 11 GI2012
  12. 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. 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 deployed19.05.2012 HSRS & CCSS 13 GI2012
  14. 14. Thank you! Hope to see you in Prague:19.05.2012 HSRS & CCSS 14 GI2012

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