This paper reports on our experience with the implementation of the Real-time Specification for Java on the Ovm open source Java virtual machine. We describe the architecture and main design decisions involved in implementing real-time Java on Ovm. We present the first use of Real-time Java in avionics in the context of control software for a ScanEagle Unmanned Aerial Vehicle.

As embedded systems increase in complexity and begin to participate in distributed systems, the need for middleware in building such systems becomes imperative. However, the use of middleware that fully implements such standards can impose a significant increase in footprint for an application, making it unsuitable for use in embedded systems. We consider the use of a standard CORBA event channel in a setting where distribution and inter-language support are unnecessary. We report our experience in applying aspects to abstract the transport layer (CORBA) of the event channel into a selectable feature. Thus, enabling or disabling CORBA for a specific application can be decided at build-time, by merely selecting CORBA as a feature. We describe the patterns used to achieve this abstraction and present footprint and throughput results showing the effect of CORBA on automatically derived subsets of the event channel.

Many of the benefits of Java, including its inherent portability, networking support, and simplicity, are of increasing importance to large-scale distributed real-time embedded (DRE) systems, but have been unavailable due to the lack of acceptable real-time performance. Recent work establishing the real-time specification for Java (RTSJ) based on Bollella et al. (2000) has led to the emergence of associated real-time Java virtual machines (RT JVMs) which promise to bridge this gap. This paper describes benchmarking results on a RT JVM in a uni-processing environment, and compares them to both C++ implementations of similar behavior and application requirements associated with large-scale avionics systems. This paper extends previously published results by Corsaro et al. (2002) and Sharp et al. (2003) by including avionics application level tests.