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A real-time java tool chain for resource constrained platforms

CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2014年第14期26卷 2407-2431页

作者： Korsholm, Stephan E. Sondergaard, Hans Ravn, Anders P. VIA Univ Coll Horsens Denmark Aalborg Univ Dept Comp Sci Aalborg Denmark

The java programming language was originally developed for embedded systems, but the resource requirements of previous and current java implementations - especially memory consumption - tend to exclude them from being used on a significant class of resource constrained embedded platforms. The contribution of this paper is an architecture and implementation of a java execution stack for resource constrained embedded platforms with a few kB of RAM and flash memory. The resource requirements of the presented architecture has been reduced significantly through all the layers of the architecture by integrating the following: (1) a lean virtual machine without any external dependencies on POSIX-like libraries or other OS functionalities;(2) a hardware abstraction layer, implemented almost entirely in java through the use of hardware objects, first level interrupt handlers, and native variables;and (3) an implementation of the Safety-Critical java profile Level 0 and 1 for hard real-time applications. All java components of a given application are minimized through program specialization, and because (2) and (3) are written in java, the program specialization has a significant impact on the resulting program size. An evaluation of the presented solution shows that the miniCDj benchmark gets reduced to a size where it can run on resource constrained platforms. Copyright (C) 2013 John Wiley & Sons, Ltd.

关键词： embedded systems java real-time java safety-critical java virtual machine

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Eliminating object reference checks by escape analysis on real-time java virtual machine

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CLUSTER COMPUTING-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND APPLICATIONS 2019年第4-Sup期22卷 S9323-S9334页

作者： Feng, Wei Shi, Xiaohua Wang, Wenru Beihang Univ Sch Comp Sci & Engn State Key Lab Software Dev Environm Beijing Peoples R China

The real-time specification for java (RTSJ) makes java to be a real-time programming language. However, the RTSJ's memory management system is more complicated than J2SE's. The assignment rules of RTSJ, which prevent the creation of dangling references, must be checked by real-time java virtual machines (JVMs) at run-time. These frequent run-time object reference checks introduce significant time overheads and unpredictable execution time, which has great impact on real-time systems. This paper presents an equivalence class based, context sensitive and flow insensitive escape analysis algorithm that effectively eliminates unnecessary run-time reference checkpoints of RTSJ programs. The optimization framework has been implemented in an open-source real-time JVM namely jRate and evaluated by CDx, a relative authority real-time java benchmark suite. The results show that this optimization algorithm eliminates more than 90% static reference checkpoints, removes about 50% run-time reference checkpoints on average, and improves the run-time performance of average 3.13%, max 8.93%.

关键词： Escape analysis Object reference check real-time java

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Simulation of safety-critical, real-time java: A case study of dynamic analysis of scoped memory consumption

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SIMULATION MODELLING PRACTICE AND THEORY 2012年 25卷 172-189页

作者： Hamza, H. Counsell, S. Brunel Univ Dept Informat Syst & Comp Uxbridge UB8 3PH Middx England

For critical, real-time applications, scoped memory management in real-time Specification for java (RTSJ) achieves a level of predictability not found in applications that use garbage collection techniques. However, a scoped memory model creates new challenges for developers. First, the reference rules between scopes constrain the design of the application's memory model. Second, there is no abstract model for scoped memory that can be applied to different applications. Third, deciding on the appropriate number of scopes and which objects or threads should be allocated into those scopes are not straightforward tasks and require tools to assist. This paper presents a simulation of a railway control system executed on the Sun RTS2.2 virtual machine: it illustrates how simulation of critical safety real-time applications in java can be used to investigate the implementation of possible scoped memory design models and their memory consumption in multi-threaded environments. The simulation demonstrates that a developer is able to compare and choose the most appropriate scoped memory design model that achieves the least memory footprint. Results showed that the memory design model with a higher number of scopes achieved the least memory footprint. However, the number of scopes per se does not always indicate a satisfactory memory footprint: choosing the right objects/threads to be allocated into scopes is an important factor to be considered. (C) 2012 Elsevier B.V. All rights reserved.

关键词： real-time simulation RTSJ scoped memory Immortal memory Memory consumption Railway control system real-time java

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Resource management policies for real-time java remote invocations

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JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING 2014年第1期74卷 1930-1944页

作者： Basanta-Val, Pablo Garcia-Valls, Marisol Univ Carlos III Madrid Dept Ingn Telemat E-28903 Getafe Spain

A way to deal with the increasing cost of next generation real-time applications is to extend middleware and high-level general-purpose programming languages, e.g. java, with real-time support that reduces development, deployment, and maintenance costs. In the particular path towards a distributed real-time java technology, some important steps have been given into centralized systems to produce real-time java virtual machines. However, the integration with traditional remote invocation communication paradigms is far from producing an operative solution that may be used to develop final products. In this context, the paper studies how The real-time Specification for java (RTSJ), the leading effort in real-time java, may be integrated with java's Remote Method Invocation (RMI) in order to support real-time remote invocations. The article details a specific approach towards the problem of producing a predictable mechanism for the remote invocation - the core communication mechanism of RMI - via having control on the policies used in the remote invocation. Results obtained in a software prototype help understand how the key entities defined to control the performance of the remote invocation influence in the end-to-end response time of a distributed real-time java application. (C) 2013 Elsevier Inc. All rights reserved.

关键词： real-time java real-time middleware RT-RMI RTSJ DRTSJ

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Enhancing OSGi with real-time java support

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SOFTWARE-PRACTICE & EXPERIENCE 2013年第1期43卷 33-65页

作者： Basanta-Val, P. Garcia-Valls, M. Estevez-Ayres, I. Univ Carlos III Madrid Dept Ingn Telemat Leganes 28911 Spain

OSGi was designed with embedded systems in mind, its current support is insufficient for coping with one main characteristic of many embedded systems: real-time performance. This article analyzes different key issues in providing OSGi with real-time java performance covering motivational issues, and different integration ways and challenges stemming from the integration. It also contributes a general framework for introducing real-time performance in OSGi, which is called the real-time for OSGi framework. The framework uses real-time java virtual machines and the real-time specification for java. The adoption of this framework allows cyber-physical systems to experience real-time java performance in their applications. The framework introduces several integration levels for OSGi and real-time specification for java, and specific real-time OSGi services. An empirical implementation was carried out using standard software, which was extended with the new defined services. Copyright (c) 2012 John Wiley & Sons, Ltd.

关键词： OSGi real-time RTSJ java real-time java

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real-time java API Specifications for High Coverage Test Generation 12

Real-time Java API Specifications for High Coverage Test Gen...

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10th International Workshop on java Technologies for real-time and Embedded Systems (JTRES)

作者： Ahrendt, Wolfgang Mostowski, Wojciech Paganelli, Gabriele Chalmers S-41296 Gothenburg Sweden Univ Twente Enschede Netherlands

ISBN: (纸本)9781450316880

We present the test case generation method and tool KeYTestGen in the context of real-time java applications and libraries. The generated tests feature strong coverage criteria, like the Modified Condition/Decision Criterion, by construction. This is achieved by basing the test generation on formal verification techniques, namely the KeY system for java source code verification. Moreover, we present formal specifications for the classes and methods in the real-time java API. These specifications are used for symbolic execution when generating tests for real-time java applications, and for oracle construction when generating tests for real-time java library implementations. The latter application exhibited a mismatch between a commercial library implementation and the official RTSJ documentation. Even if there is a rationale behind this particular inconsistency, it demonstrates the effectiveness of our method on production code.

关键词： test generation real-time java coverage

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The design and performance of real-time java middleware

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2003年第11期14卷 1155-1167页

作者： Corsaro, A Schmidt, DC Washington Univ Dept Comp Sci & Engn St Louis MO 63130 USA Vanderbilt Univ Inst Software Integrated Syst Nashville TN 37235 USA

More than 90 percent of all microprocessors are now used for real-time and embedded applications. The behavior of these applications is often constrained by the physical world. It is therefore important to devise higher-level languages and middleware that meet conventional functional requirements, as well as dependably and productively enforce real-time constraints. This paper provides two contributions to the study of languages and middleware for real-time and embedded applications. We first describe the architecture of jRate, which is an open-source ahead-of-time-compiled implementation of the RTSJ middleware. We then show performance results obtained using RTJPerf, which is an open-source benchmarking suite that systematically. compares the performance of RTSJ middleware implementations. This paper shows that, while research remains to be done to make RTSJ a bullet-proof technology, the initial results are promising. The performance and predictability of jRate provides a baseline for what can be achieved by using ahead-of-time compilation, Likewise, RTJPerf enables researchers and practitioners to evaluate the pros and cons of RTSJ middleware systematically as implementations mature.

关键词： real-time middleware real-time java QoS-enabled middleware platforms object-oriented languages real-time resource management performance evaluation

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AUTOMATIC MEMORY MANAGEMENT FOR EMBEDDED real-time java PROCESSOR JPOR-32

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INTELLIGENT AUTOMATION AND SOFT COMPUTING 2011年第8期17卷 1193-1205页

作者： Hu, Guang Chai, Zhilei Tu, Shiliang Fudan Univ Sch Comp Sci Shanghai 200433 Peoples R China Shanghai Int Studies Univ Dept Comp Sci Shanghai 200083 Peoples R China Jiangnan Univ Sch Informat Technol Wuxi 214122 Peoples R China

Currently, java has been gradually applied in embedded real-time areas like robotics, control system, etc. owning to its advantages like robustness, security, etc. In order to improve the performance of java's execution engine for embedded real-time applications, JPOR-32, an embedded real-time java processor, is designed. Based on it, this paper presents the automatic memory management (AMM) mechanism for embedded real-time java processor. JPOR-32 provides architectural support as well as instruction level support for AMM. Its preprocessing mechanism reduces the complexity of the implementation of AMM, enhances the run-time efficiency, and promotes predictability of the worst-case execution time. The system design of JPOR-32 makes AMM of class area avoided, and the optimized design of instruction set provides effective support for space checking and garbage collection scheduling. This paper also proposes an object reference format which provides supports for objects tracing, heap scanning, synchronization, etc., and lays the foundation for the implementation of suitable garbage collection algorithm. Moreover, this paper gives the analysis of the feature of runtime environment of embedded java processor, and implements a suitable improved generational garbage collector.

关键词： memory management garbage collector java processor real-time java embedded system intelligent automation

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Ravenscar-java: a high-integrity profile for real-time java

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2005年第5-6期17卷 681-713页

作者： Kwon, J Wellings, A King, S Univ York Dept Comp Sci Real Time Syst Res Grp York YO10 5DD N Yorkshire England

For many, java is the antithesis of a high-integrity programming language. Its combination of object-oriented programming features, its automatic garbage collection, and its poor support for real-time multi-threading are all seen as particular impediments. The real-time Specification for java has introduced many new features that help in, the real-time. domain. However, the expressive power of these features means that very complex programming models can be created, necessitating complexity in the supporting real-time virtual machine. Consequently, java, with the real-time extensions as they stand, seems too complex for confident use in high-integrity systems. This paper presents a java profile for-the development of software-intensive high-integrity real-time systems. This restricted programming model removes language features with high overheads and complex semantics, on which it is hard to perform timing and functional analyses. The profile fits within the J2ME framework and is consistent with well-known guidelines for high-integrity software development, such as those defined by the U.S. Nuclear Regulatory Commission. Copyright (c) 2005 John Wiley & Sons, Ltd.

关键词： high-integrity systems real-time java profile

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Design of Instruction Execution Stage for an Embedded real-time java Processor

Design of Instruction Execution Stage for an Embedded Real-T...

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International Conference on Intelligent Computing and Information Science

作者： Hu, Guang Chai, Zhilei Zhao, Wenke Shanghai Int Studies Univ Dept Comp Sci Shanghai 200086 Peoples R China Fudan Univ Sch Comp Sci Shanghai 200433 Peoples R China Jiangnan Univ Sch Internet Things Wuxi 214122 Peoples R China Intel Corp Intel Asia Pacific Res & Dev Ltd Shanghai 200241 Peoples R China

ISBN: (纸本)9783642181337

Now, as a popular language for the development of sever and desktop applications, java is also playing a more and more important role in embedded development owning to its features like platform independence, high development efficiency, etc. Accordingly, JPOR-32, a 32-bit java processor optimized for real-time specification for java, is designed. In this paper, taking JPOR-32 as an example, the instruction execution stage design for embedded real-time java processor is presented. The run time operand stack and method stack is implemented, which lays the foundations of execution of instruction set based on stack. For instruction execution stage, this paper presents on emphasis the control signal operation mechanism and the instruction execution stage data path.

关键词： java processor real-time java instruction execution real-time system

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