CQL

The gt-cql module a human readable “Contextual Query Language” for writing filter expressions for working with geospatial information.

CQL was originally known as Common Query Language (so you will find lots of examples that still refer to this name). The standard comes out of library science and was picked up by the OGC when they were implementing their catalog server specification.

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gt-cql module

For our purposes it provides a great human readable way to expression Filter similar to an SQL “where clause”. Indeed we have our own extension that allows you to represent the full range of GeoTools Filter and Expression ideas using simple text strings.

Maven:

<dependency>
  <groupId>org.geotools</groupId>
  <artifactId>gt-cql</artifactId>
  <version>${geotools.version}</version>
</dependency>

References

CQL2

CQL2 is OGC evolution of CQL designed for use in OGC APIs. Unlike CQL/ECQL, it is not limited to a human readable text encoding, but also provides a JSON encoding (an equivalent to the XML encoding of Filter and Expression).

Maven:

<dependency>
  <groupId>org.geotools</groupId>
  <artifactId>gt-cql2-text</artifactId>
  <version>${geotools.version}</version>
</dependency>
<dependency>
  <groupId>org.geotools</groupId>
  <artifactId>gt-cql2-json</artifactId>
  <version>${geotools.version}</version>
</dependency>

** References **

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