The RTSJ is the specification resulting from JSR-1, the first specification launched through the Java® Community Process. The specification was approved in January 2002. The first commercial implementation followed in Spring of 2003. The second release of the reference implementation (RI) was in Spring 2004, and version 1.0.1 of the RTSJ was released (with updates to the RI and Technology Compatibility Suite) in June 2005.

RTSJ is designed to support both hard and soft real-time applications. Among its major features are: scheduling properties suitable for real-time applications with provisions for periodic and sporadic tasks, support for deadlines and CPU time budgets, and tools to let tasks avoid garbage collection delays

8/6/2008: 1.0.2 RI updated to version 6. TCK updated to version 3.0.13. Alpha 1.1 RI updated to version 5.
See download page.