20.11. Composite Converters

Composite converters are designed to allow processing of mixed data streams. Each message that comes in can be routed to a separate converter definition based on a predicate. Currently composite converters are available for the Delimited Text Converter and the JSON Converter.

20.11.1. Predicates

Predicates are an extension of the normal converter transform language. The inputs to the expression will vary depending on the converter being used, but generally the inputs are available using the standard expressions $0, $1, etc. Operators are defined that allow comparisons between different transform expressions. Each predicate must evaluate to a Boolean true or false, generally using a comparison operator. The normal transform functions are available (see Transformation Function Overview).

The following operators are defined: ==, !=, >, >=, <, <=, !, &&, ||

Operators can be grouped using parenthesis, for example $0 == 'a' && ($1 == 'b' || $2 == 'c')

Note that the comparison operators (>, >=, <, <=) can only operate on comparable types (e.g. primitive ints, doubles, etc, or any class implementing java.lang.Comparable).