You can write custom business logic using Adempiere to extend adempiere function.
Java SE 6 will contain JSR 223: Scripting for the JavaTM Platform API classes. This Framework can be used to host Script Engines in Java Applications.
Goorvy is an agile and dynamic language for the Java Virtual Machine which makes modern programming features available to Java developers with almost-zero learning curve. It supports Domain-Specific Languages and other compact syntax so your code becomes easy to read and maintain. In Adempiere, it seamlessly integrates with all existing Java classes and libraries and compiles straight to Java bytecode so you can use it anywhere you can use Java