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OGC

10 December 2010 – The Open Geospatial Consortium (OGC®) announces adoption and availability of the OGC Georeferenced Table Joining Service (TJS) Implementation Standard, Version 1.0. The TJS standard is available for free download at http://www.opengeospatial.org/standards/tjs.

The OGC TJS standard defines an interface for services that provide the ability to join attribute data stored in one database on a network with corresponding geometry (points, lines, or polygons) stored in another network accessible database.

… more

I just stumbled upon the following handy Firefox plugin:

WMS Inspector provides a set of tools for integrators and developers that work with the Web Map Service (WMS) standard. It aims to ease repetitive tasks like debugging requests or checking which individual services are used from an online mapping application. It also focuses on provide a user-friendly output of the different services’ capabilities.

https://addons.mozilla.org/en-US/firefox/addon/91406/

The OGC filter encoding standard – for whatever reason – lacks the useful IN operator we know and love from other languages like SQL [1]. Geoserver developers have therefore implemented this functionality as a non-standard SLD function [2]. Unfortunately this implementation requires prior knowledge of the number of arguments in the IN clause and it’s limited to 10 arguments.

An example filter would look like this:

<ogc:Filter>
   <ogc:PropertyIsEqualsTo>
       <ogc:Function name="in3">
          <ogc:PropertyName>first_name</ogc:PropertyName>
          <ogc:Literal>Paul</ogc:Literal>
          <ogc:Literal>Mary</ogc:Literal>
          <ogc:Literal>Luke</ogc:Literal>
       </ogc:Function>
       <ogc:Literal>true</ogc:Literal>
   </ogc:PropertyIsEqualsTo>
</ogc:Filter>

[1] https://underdark.wordpress.com/2010/06/14/the-missing-in-operator-ogc-filter-standards/
[2] http://docs.geoserver.org/stable/en/user/styling/sld-tipstricks/mixed-geometries.html#using-non-standard-sld-functions

It sounds incredible, but it’s true: OGC Filter Encoding in it’s current version 1.1 lacks an IN operator [1]. Combining multiple PropertyIsEqualTo using ORs performs really badly both on Arcgis Server [2] and Geoserver [3]. That calls for the implementation of this standard-exceeding IN operator. Maybe PropertyIsIn?

[1] http://www.opengeospatial.org/standards/filter
[2] http://viswaug.wordpress.com/2009/01/20/filter-encoding-standard-11-and-the-curious-case-of-the-missing-in-operator/
[3] https://underdark.wordpress.com/2010/06/10/dynamic-styling-and-filtering-of-a-geoserver-wms-using-openlayers-layer-wms-post/

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