Attribute filters

Attribute filters in a GeoEvent Service filter events based on attribute criteria. An attribute filter can be configured with one or more attribute expressions. The logical combination of these expressions represents the criteria a GeoEvent must satisfy to pass through the filter.

The following attribute operators are supported:

• Equal (=)—This operator retains GeoEvents whose attribute values equal a specified value. For example, IdString = 3XAB891
• Not Equal (!=)—This operator retains GeoEvents whose attribute values do not equal a specified value. For example, StatusString != Err.

  Remarque :

  The Equals and Not Equal operators should not be applied to floating point values. For example, do not configure a filter expression like Radius = 3.14159, instead use the Greater Than, Less Than, or other operator.

• Greater Than (>)— This operator retains GeoEvents whose attribute values are greater than a specified value. For example, Speed > 50.
• Greater Or Equal (>=)—This operator retains GeoEvents whose attribute values are greater than or equal to a specified value. For example, Speed >= 50.
• Less Than (<)—This operator retains GeoEvents whose attribute values are less than a specified value. For example, Altitude < 1000.
• Less Or Equal (<=)—This operator retains GeoEvents whose attribute values are less than or equal to a specified value. For example, Altitude <= 1000.

  Remarque :

  The Greater Than, Less Than, and other operators should not be applied to string values. For example do not configure a filter expression like Company > ABC, instead use the Equals or Not Equal operator and incorporate the entire string into the expression.

• IN— This operator retains GeoEvents when a specified field's value exists in a comma-separated list of values. For example, StatusCode IN HK1,HK3,HK5.
• MATCHES—This operator retains GeoEvents when a specified field's value matches a regular expression. For example, StatusCode MATCHES ^HK[135].

  Remarque :

  The specified regular expression is evaluated as either matching or not matching the entire event field value; partial matches are not supported. In the example above, if the StatusCode contained additional characters beyond the single numeric digit, the expression would need to include .* to match any trailing characters in the attribute value.

• EXISTS—This operator retains GeoEvents when a specified field exists in the received event's schema. For example, Geometry EXISTS.
• ISNULL—This operator retains GeoEvents when a specified field contains a null value. For example, Geometry ISNULL.

Remarque :

Checking for NULL strings is not supported. GeoEvent defines a string as empty (a zero-length string) rather than as a null object.