Applying Java to the Domain of Hard Real-Time Systems

International audienceOrganizations are attracted to Java because the language has proven more economical than C and C++. Companies that have made the switch to Java typically find that they are twice as productive during development of new functionality and five to ten times as productive during reuse of existing code. Organizations that develop in Java also observe decreased software error rates, increased software reuse and longevity, and improved recruitment of competent developers. Special hard real-time Java development practices enable proofs of resource needs and determinism. Early analysis demonstrates that the hard real-time Java platform runs in less than a tenth the memory footprint and up to three times faster than traditional Java for typical hard real-time tasks. Determinism is on par with typical C code, offering more than a 20-fold improvement over the timing predictability of traditional Java

Safety-critical Java for embedded systems

This paper presents the motivation for and outcomes of an engineering research project on certifiable Java for embedded systems. The project supports the upcoming standard for safety-critical Java, which defines a subset of Java and libraries aiming for development of high criticality systems. The outcome of this project include prototype safety-critical Java implementations, a time-predictable Java processor, analysis tools for memory safety, and example applications to explore the usability of safety-critical Java for this application area. The text summarizes developments and key contributions and concludes with the lessons learned

A Methodology for Transforming Java Applications Towards Real-Time Performance

The development of real-time systems has traditionally been based on low-level programming languages, such as C and C++, as these provide a fine-grained control of the applications temporal behavior. However, the usage of such programming languages suffers from increased complexity and high error rates compared to high-level languages such as Java. The Java programming language provides many benefits to software development such as automatic memory management and platform independence. However, Java is unable to provide any real-time guarantees, as the high-level benefits come at the cost of unpredictable temporal behavior.This thesis investigates the temporal characteristics of the Java language and analyses several possibilities for introducing real-time guarantees, including official language extensions and commercial runtime environments. Based on this analysis a new methodology is proposed for Transforming Java Applications towards Real-time Performance (TJARP). This method motivates a clear definition of timing requirements, followed by an analysis of the system through use of the formal modeling languageVDM-RT. Finally, the method provides a set of structured guidelines to facilitate the choice of strategy for obtaining real-time performance using Java. To further support this choice, an analysis is presented of available solutions, supported by a simple case study and a series of benchmarks.Furthermore, this thesis applies the TJARP method to a complex industrialcase study provided by a leading supplier of mission critical systems. Thecase study proves how the TJARP method is able to analyze an existing and complex system, and successfully introduce hard real-time guaranteesin critical sub-components

Exhaustive testing of safety critical Java

With traditional testing, the test case has no control over non-deterministic scheduling decisions, and thus errors dependent on scheduling are only found by pure chance. Java Path Finder (JPF) is a specialized Java virtual machine that can systematically explore execution paths for all possible schedulings, and thus catch these errors. Unfortunately, execution-based model checkers, including JPF, cannot be easily adapted to support real-time programs. We propose a scheduling algorithm for JPF which allows testing of Safety Critical Java (SCJ) applications with periodic event handlers at SCJ levels 0 and 1 (without aperiodic event handlers). The algorithm requires that deadlines are not missed and that there is an execution time model that can give best- and worst-case execution time estimates for a given program path and specific program inputs. Our implementation, named R SJ, allows to search for scheduling dependent memory access errors, certain invalid argument errors, priority ceiling emulation protocol violations, and failed assertions in application code in SCJ programs for levels 0 and 1. It uses the execution time model of the Java Optimized Processor (JOP). We test our tool wit

High-Performance Transactional Event Processing

Abstract. This paper presents a transactional framework for low-latency, high-performance, concurrent event processing in Java. At the heart of our framework lies Reflexes, a restricted programming model for highly responsive systems. A Reflex task is an event processor that can run at a higher priority and preempt any other Java thread, including the garbage collector. It runs in an obstruction-free manner with time-oblivious code. We extend Reflexes with a publish/subscribe communication system, itself based on an optimistic transactional event processing scheme, that provides efficient coordination between time-critical, low-latency tasks.We report on the comparison with a commercial JVM, and show that it is possible for tasks to achieve 50 µs response times with way less than 1% of the executions failing to meet their deadlines.

Real-Time Operating Systems and Programming Languages for Embedded Systems

In this chapter, we present the different alternatives that are available today for the development of real-time embedded systems. In particular, we will focus on the programming languages use like C++, Java and Ada and the operating systems like Linux-RT, FreeRTOS, TinyOS, etc. In particular we will analyze the actual state of the art for developing embedded systems under the WORA paradigm with standard Java [1], its Real-Time Specification and with the use of Real-Time Core Extensions and pico Java based CPUs [5]. We expect the reader to have a clear view of the opportunities present at the moment of starting a design with its pros and cons so it can choose the best one to fit its case.Fil: Orozco, Javier Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Laboratorio de Sistemas Digitales; ArgentinaFil: Santos, Rodrigo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Laboratorio de Sistemas Digitales; Argentin