A Real-Time RMI Framework for the RTSJ

The Real-Time Specification for Java (RTSJ) provides a platform for the development of real-time applications. However, the RTSJ does not take the distribution requirements of real-time applications into consideration. As distribution in Java is often implemented using Java’s Remote Method Invocation (RMI), a real-time version of RMI between RTSJ implementations can provide a platform for writing distributed real-time systems. This report describes a Real-Time RMI (RT-RMI) framework that supports timely invocation of remote objects. The thread classes defined by the RTSJ are used to provide the client and server threading mechanisms in the invocation process. The memory model of the RTSJ is considered to ensure that these threads correctly use memory areas and avoid memory leaks in the absence of the garbage collector. New classes are developed to control the threads used throughout the invocation and to provide new semantics for remote objects that can be invoked in a timely fashion. An extended example is provided to show how an application would use an implementation of the framework. Additional support required for the real-time environment beyond end-to-end timeliness in invocation is discussed. Finally, a prototype that implements the framework is described.