Grails provides great declarative UI and persistence. But that still leaves all the business logic portion of your apps to be written (and tested and maintained) by hand. That’s often 25%-50% of the final code base.

ABL complements Grails by automating business logic using simple annotations like sums, counts, and multi-table formulas and constraints. This ends up looking more like spreadsheet formulas than complex code - easier to understand for IT and business users.

ABL’s open-source engine is integrated into GORM as an event listener.  That means there are no API changes: your logic is automatically executed on commit, in the correct order, and re-used across use cases.

Project home: https://sourceforge.net/projects/autobuslogic

Demo: http://goo.gl/jFiY1