Apama mapping tools use an expression-based mapping layer to map between Apama events and external message payloads. The expressions use Java Unified Expression Language (EL) resolvers and methods, which must be registered to the mapping layer. Apama includes a set of EL resolvers and EL methods that are registered for you and that you can use in mapping expressions. If you want you can register your own EL resolvers and EL methods and then use them as custom mapping extensions.

See Using custom EL mapping extensions .