XAL Application Programming Structure

XAL is an application programming framework used at the Spallation Neutron Source (SNS) project in Oak Ridge. It is written in Java, and provides users with a hierarchal view of the accelerator. Features include database configuration of the accelerator structure, an online envelope model that is configurable from design or live machine values, an application framework for quickstart GUI development, a scripting interface for algorithm development, and a common toolkit for shared resources. To date, about 25 applications have been written, many of which are used extensively in the SNS beam commissioning activities. The XAL framework and example applications will be discussed.