Abstract — A memory model based on scoped areas is one of the distinctive features of the Real-Time Specification for Java (RTSJ). Scoped Types ensure timely reclamation of memory and predictable performance. The price to pay for these benefits is an unfamiliar programming model that, at the same time, is complex, requires checking all memory accesses, and rewards design-time errors with run-time crashes. We investigate an alternative approach, referred to as Scoped Types, that simplifies the task of managing memory in real-time codes. The key feature of our proposal is that the run-time partition of memory imposed by scoped areas is straightforwardly mirrored in the program text. Thus cursory inspection of a program reveals which objects will inhabit the different scopes, significantly simplifying the task of understanding real-time Java programs. Moreover, we introduce a type system which ensures that no run-time errors due to memory access checks will occur. Thus a RTSJ-compliant virtual machine does not require memory access checks. The contributions of this paper are the concept of Scoped Types, and a proof soundness of the type system. Experimental results will be described in future work. I.

ed for the DARPA PCES Capstone Demo We report on our experience with the implementation of the Real-time Specification for Java (RTSJ) in the DARPA Program Composition for Embedded System (PCES) program. Within the scope of PCES, Purdue University and the Boeing Company collaborated on the development of Ovm, an open source implementation of the RTSJ virtual machine. Ovm was deployed on a ScanEagle Unmanned Aerial Vehicle and successfully flight tested during the PCES Capstone Demonstration. ployed in the ScanEagle UAV to implement utation, threat deconfliction algorithms tion between the Boeing Corporation, ersity, DLTech, UCI, WUSTL itecture by focusing one ol, threat assessment, and 1.

The Real-time Specification for Java extends the Java platform

Abstract. The paper gives an overview of RTJBench, a framework designed to assist in the task of benchmarking programs written in the Real-Time Specification for Java, but with potentially more general applicability. RTJBench extends the JUnit framework for unit testing of Java applications with tools for real-time environment configuration, simple data processing and configurable graphical presentation services. We present design principles of RTJBench and give an example of a benchmarking suite we have been using for daily regression benchmarking of the Open Virtual Machine. Keywords: Benchmarking, regression benchmarking, Real-Time Specification for Java

While managed languages such as C # and Java have become quite popular in enterprise computing, they are still considered unsuitable for hard real-time systems. In particular, the presence of garbage collection has been a sore point for their acceptance for low-level system programming tasks. Realtime extensions to these languages have the dubious distinction of, at the same time, eschewing the benefits of highlevel programming and failing to offer competitive performance. The goal of our research is to explore the limitations of high-level managed languages for real-time systems programming. To this end we target a real-world embedded platform, the LEON3 architecture running the RTEMS real-time operating system, and demonstrate the feasibility of writing garbage collected code in critical parts of embedded systems. We show that Java with a concurrent, real-time garbage collector, can have throughput close to that of C programs and comes within 10 % in the worst observed case on realistic benchmark. We provide a detailed breakdown of the costs of Java features and their execution times and compare to real-time and throughput-optimized commercial Java virtual machines.