MapServer Filter Encoding (FE) HowTo

To be able to use Filter Encoding, you need to create a valid WFS server using MapServer. Please refer to the WFS HowTo for specifics.

There is nothing special that should be added to a WFS server for Filter Encoding, but you should note that, when requesting the capabilities of your WFS server, the document returned should contain the supported filters. Here is part of a Capabilities document as well as the Post support:

<?xml version='1.0' encoding="ISO-8859-1" ?>
<WFS_Capabilities
   version="1.0.0"
   updateSequence="0"
   xmlns="http://www.opengis.net/wfs"
   xmlns:ogc="http://www.opengis.net/ogc"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.opengis.net/wfs http://ogc.dmsolutions.ca/wfs/1.0.0/WFS-capabilities.xsd">

<!-- MapServer version 4.1 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP
OUTPUT=PDF OUTPUT=SWF SUPPORTS=PROJ SUPPORTS=FREETYPE SUPPORTS=WMS_SERVER
SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT INPUT=POSTGIS
INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE -->

<Service>
  <Name>MapServer WFS</Name>
  <Title>GMap WMS Demo Server</Title>
  <OnlineResource>http://localhost/cgi-bin/mapserv.exe?map=
    c:/msapps/wfs_filter/htdocs/ns_wfsserver.map&</OnlineResource>
</Service>

<Capability>
  <Request>
    <GetCapabilities>
      <DCPType>
        <HTTP>
          <Get onlineResource="http://localhost/cgi-bin/mapserv.exe?map=
            c:/msapps/wfs_filter/htdocs/ns_wfsserver.map&" />
        </HTTP>
      </DCPType>
      <DCPType>
        <HTTP>
          <Post onlineResource="http://localhost/cgi-bin/mapserv.exe?map=
            c:/msapps/wfs_filter/htdocs/ns_wfsserver.map&" />
        </HTTP>
      </DCPType>
    </GetCapabilities>
    ...
  </Request>
</Capability>
...
<Filter_Capabilities>
  <Spatial_Capabilities>
    <Spatial_Operators>
             <Intersect/>
             <DWithin/>
           <BBOX/>
    </Spatial_Operators>
  </Spatial_Capabilities>
  <Scalar_Capabilities>
    <Logical_Operators />
    <Comparison_Operators>
      <Simple_Comparisons />
      <Like />
      <Between />
    </Comparison_Operators>
  </Scalar_Capabilities>
</Filter_Capabilities>

</WFS_Capabilities>
      

To be able to generate a Filter to a WFS server, a layer level metadata called wfs_filter has been added, which should contain the filter to be sent to the server. Following is an example of a valid WFS client layer with a filter:

LAYER
  NAME popplace
  METADATA
    "wfs_filter" "<PropertyIsGreaterThan><PropertyName>POP_RANGE</PropertyName><Literal>4
      </Literal></PropertyIsGreaterThan>"

  END

  TYPE POINT
  STATUS ON

  PROJECTION
    "init=epsg:42304"
  END

  CONNECTIONTYPE WFS
  CONNECTION "http://www2.dmsolutions.ca:8090/cgi-bin/mswfs_filter?SERVICE=WFS&VERSION=1.0.0
    &TYPENAME=popplace"

  LabelItem "Name"
# LabelItem "Pop_range"
  CLASSITEM "Capital"
  CLASS

    TEMPLATE "ttt_query.html"
    SYMBOL 2
    SIZE 8

    NAME "Cities"
    LABEL
      COLOR  255 0 0
      FONT fritqat-italic
      TYPE truetype
      SIZE 8
      POSITION AUTO
      #PARTIALS FALSE
      OUTLINECOLOR 255 255 255
      FORCE TRUE

    END
    COLOR 0 0 0
  END

  TOLERANCE 5
END # Layer
      

Things to note:

Copyright (c) 2004, Yewondwossen Assefa, DM Solutions Group Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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