Real-time Java in modernization of the aegis weapon system

Abstract

The U.S. Navy's Aegis system, considered to be the "shield of the fleet", provides area air defense for a carrier battle group in addition to providing long-range ballistic missile defense. A typical Aegis deployment consists of about 100 computers, many of which have multiple cores. The application is distributed, with typical real-time threads spanning 4 or 5 different computers. End-to-end distributed thread timing constraints measured from stimulus to response are typically under 100 ms. The target jitter constraints on the individual contributions of processors to the end-to-end deadline constraint are well below 1 ms. The system is fully redundant to support fault tolerance. The software is considered to be safety critical because it aims and fires weapons. The Aegis Weapons System software was recently rewritten into real-time Java as part of the Aegis Modernization activity. This project involved replacement of about 200,000 lines of CMS-2 and Ada code with roughly 500,000 lines of Java. The effort began in 2003 and the new Java implementation of Aegis Weapons System is now being deployed on warships. This paper describes the motivation for the modernization effort and provides a summary of Lockheed Martin's experiences with this project.