The Real-Time Specification for Java/spl trade/ (RTSJ) is an API specification that allows developers to write real-time applications using the Java programming language. Project Mackinac is the code name of Sun Microsystems' RTSJ development effort. This paper reviews the main requirements from the RTSJ itself, presents additional requirements defined by the Mackinac implementation team, explains various implementation strategies used to meet the requirements, and presents performance results from tests executed against the current development version of Mackinac.

We present a scheduling architecture that enables the implementation of deadline based scheduling policies. The architecture is used to give real time capabilities to a custom Java virtual machine. This framework retains a clear separation between generic kernel mechanisms and upper level scheduling classes. A pure earliest deadline first algorithm can be implemented, but enhanced policies such as D/sup over/ or Robust EDF are also supported. We present our architecture, its implementation in the ChorusOS microkernel and its use by the Java virtual machine.