Java Expression Language (JEXL) is an expression language engine which can be
embedded in applications and frameworks. JEXL is inspired by Jakarta Velocity
and the Expression Language defined in the JavaServer Pages Standard Tag
Library version 1.1 (JSTL) and JavaServer Pages version 2.0 (JSP). While
inspired by JSTL EL, it must be noted that JEXL is not a compatible
implementation of EL as defined in JSTL 1.1 (JSR-052) or JSP 2.0 (JSR-152).
For a compatible implementation of these specifications, see the Commons EL
project.

JEXL attempts to bring some of the lessons learned by the Velocity community
about expression languages in templating to a wider audience. Commons Jelly
needed Velocity-ish method access, it just had to have it.