Apache Jelly is a Java and XML based scripting and processing engine for turning XML into executable code.〔http://commons.apache.org/jelly/〕 Jelly is a component of Apache Commons. Custom XML languages are commonly created to perform some kind of processing action. Jelly is intended to provide a simple XML based processing engine that can be extended to support various custom actions.〔http://commons.apache.org/jelly/overview.html〕 ==Use by Clarity Software== Clarity PPM Software, a product of CA Technologies, uses Jelly and an additional custom tag library extensively in the implementation of its XML Open Gateway application architecture. The Clarity language is known as GEL (Generic Execution Language) and is a scripting language that is based on the Jelly libraries. The following example shows how Clarity implements the classical "Hello World" application.〔https://support.ca.com/cadocs/1/m000471e.pdf Clarity Integration Guide 8.1〕 Hello World $!