MVEL started out as an expression evaluator for the Valhalla project, and while Valhalla itself is dormant, MVEL lives on, like a pearl plucked out of a dying oyster.
Some have compared it to OGNL, JEXL or JUEL, but that's a mistake. In terms of features, performance, ease of use and integration, MVEL is in a class of its own. MVEL solves problems, namely the problems encompassing the domain of embedded scripting.
Not convinced? Interested in learning more? Check out the exclusive TSS article written by Mark Proctor, the Drools Project Lead at Red Hat, and Mike Brock, the MVEL and Errai Project Leads at Red Hat.
Learn more about MVEL and the JDK.