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Extending the concurrency model of the real-time specification for java

CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2011年第14期23卷 1623-1645页

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

The current RTSJ (real-time Specification for java) threading model is dualized: a programmer has to decide between the high predictability offered by the region-based model and the flexibility offered by the garbage collection. So far, there is no unique type of thread which offers both the high predictability of a non-heap thread and the flexibility of a real-time thread in a single entity. Furthermore, this lack has a serious impact on the programmer who has to deal with new and sometimes non-trivial to use mechanisms, such as specific queues of objects or new types of threads, in order to avoid the priority inversion caused by the garbage collector. In order to tackle the concern properly and provide an improved and more generalized programming model, the authors propose a simple extension to the current threading model named realtimeThread++, in an attempt to introduce more flexibility in the RTSJ concurrency model. The paper describes the extension from several points of view: (i) the programmer, identifying scenarios that may benefit from it significantly;(ii) the real-time java technology perspective, identifying changes required in the current real-time virtual machine to support it;and (iii) the accumulated experience, relating empirical results obtained from a software prototype that supports the extension. Copyright (C) 2010 John Wiley & Sons, Ltd.

关键词： real-time java concurrency models memory management RTSJ

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An Architecture for Distributed real-time java based on RMI and RTSJ

An Architecture for Distributed Real-Time Java based on RMI ...

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15th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)

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

ISBN: (纸本)9781424468508

Today's trend in real-time systems reveals the necessity of new technologies to easy their development and maintenance. Among others, some interesting alternatives are found in high-level real-time programming languages, better development models, or simple architectures and models. From the perspective of real-time java, a recent real-time programming language, this paper offers an architecture (and its corresponding java interfaces) to help the development of an upcoming distributed real-time technology for java (named DRTSJ). To that end it describes a neutral architecture based on java's Remote Method Invocation (RMI) and The real-time Specification for java (RTSJ). The empirical evidences included in the paper offer also interesting clues on the performance this technology may deliver.

关键词： RTSJ DRTSJ real-time java middleware

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Memory Access Mechanism in Embedded real-time java Processor

Memory Access Mechanism in Embedded Real-Time Java Processor

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2nd International Conference on Computer and Automation Engineering (ICCAE)

作者： Hu, Guang Chai, Zhilei Tu, Shiliang Fudan Univ Dept Comp Sci & Engn Shanghai Peoples R China Shanghai Int Studies Univ Dept Comp Sci Shanghai Peoples R China Jiangnan Univ Sch Informat Technol Ctr Intelligent & High Performance Comp Wuxi Peoples R China

ISBN: (纸本)9781424455690

Currently, java has been gradually applied in such areas as robotics, industrial control, and other embedded real-time applications owning to its advantages like platform independence, robustness, security, etc. In order to improve the performance of java's execution engine for embedded real-time applications, an embedded real-time java processor JPOR-32 (32-bit java Processor Optimized for RTSJ) is designed. In this paper, the memory access mechanism of JPOR-32 is presented. In JPOR-32, the optimized memory organization structure is designed to implement the runtime data areas of the java virtual machine (JVM). Based on it, with the preprocessing operation, the memory access instructions optimization is implemented as well. The preprocessing operation enables the JVM's runtime operations involving dynamic loading, verification, preparation, resolution, etc. to be handled in advance. It not only provides an efficient and convenient way to implement memory access, but also makes the contribution to the WCET predictability. As to the memory management, in accordance with the real-time Specification for java (RTSJ), garbage collection (GC) is not allowed in the immortal memory as well as the scoped memory, and in the heap, JPOR-32 adopts improved GC scheme suitable for embedded real-time java environment. Besides, with the architectural support of the pipelined datapath, JPOR-32 provides effective supports for efficient and predictable memory access.

关键词： memory access java processor embeeded real-time java

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***: Visual test and debug queries for hard real-time

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2014年第14期26卷 2456-2487页

作者： Blanton, Ethan Lessa, Demian Arora, Puneet Ziarek, Lukasz Jayaraman, Bharat Fiji Syst Inc South Bend IN 46637 USA SUNY Buffalo Buffalo NY USA

Hard real-time systems have stringent timing and resource requirements. As such, debugging and tracing such systems often requires low-level hardware support, and online debugging is usually precluded entirely. In other areas, however, visual debugging has greatly improved program understanding and late cycle development times for nonreal-time applications. In this paper, we introduce a visual test and debug framework for hard real-time java applications built around the JIVE platform and realized in the Fiji virtual machine. Our framework, called *** ["dZIfi], provides high-level debugging support over low-level execution traces. *** provides both powerful visualizations and real-time centric temporal query support. To ensure preservation of the real-time characteristics of the application being tested and debugged, *** leverages a real-time event log infrastructure that logs only relevant application and virtual machine level events, such as synchronization and modifications to priorities or thread state. Our performance results indicate that our logging infrastructure is suitable for hard real-time systems, as the performance impact is both uniform and quantifiable. Copyright (C) 2013 John Wiley & Sons, Ltd.

关键词： real-time java visual debugging query-based debugging

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NO-Heap Remote Objects for Distributed real-time java

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ACM TRANSACTIONS ON EMBEDDED COMPUTING SYSTEMS 2010年第1期10卷 7-7页

作者： Basanta-Val, Pablo Garcia-Valls, Marisol Estevez-Ayres, Iria Univ Carlos III Madrid Dept Ingn Telemat Madrid 28911 Spain

This article presents an approach to providing real-time support for java's Remote Method Invocation (RMI) and its integration with the RTSJ memory model in order to leave out garbage collection. A new construct for remote objects, called No-heap Remote object (NhRo), is introduced. The use of a NhRo guarantees that memory required to perform a remote invocation (at the server side) does not use heap memory. Thus, the aim is to avoid garbage collection in the remote invocation process, improving predictability and memory isolation of distributed java-based real-time applications. The article presents the bare model and the main programming patterns that are associated with the NhRo model. Sun RMI implementation has been modified to integrate the NhRo model in both static and dynamic environments.

关键词： Design Experimentation real-time java real-time remote objects region-based memory management distributed real-time java RTSJ DRTSJ

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Distributed java Auction Module on real-time CORBA

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REVISTA IBEROAMERICANA DE AUTOMATICA E INFORMATICA INDUSTRIAL 2012年第4期9卷 406-416页

作者： Basanta-Val, P. Garcia-Valls, M. Morillas-Rodrigo, H. Cano-Romero, J. Univ Carlos III Madrid Dept Ingn Telemat Madrid 28911 Leganes Spain

Using middleware infrastructures that enable communication among different nodes in a system may alleviate aspects related to management and development cost in flexible environments. In that context the article presents an auction architecture with certain real-time requirements that have to be satisfied. The architecture implements a continuous double action (CDA) algorithm for a real-time middleware. The article describes the architecture (actors and goals) and the results obtained by using common-off-the-shelf real-time middleware.

关键词： Action Systems real-time Middleware Industrial informatics RT-CORBA real-time java

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Performance Analysis of a real-time java Execution Environment for IEC 61499

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IFAC Proceedings Volumes 2009年第4期42卷 984-989页

作者： Kleanthis C. Thramboulidis George S. Doukas Alkiviadis Zoupas Electrical and Computer Engineering University of Patras 26500 Greece

The IEC 61499 standard enhances the 1131 Function Block model to exploit the advantages of the object technology in the industrial automation domain. Several prototype development environments have been developed by various research groups and the first commercial tools that support this model are already in the market. However, the absence of mature run-time environments that will allow the execution of IEC 61499 compliant applications is still evident. Even for the existing ones, there is no evidence about their efficiency to meet real-time constraints imposed by this kind of applications. Benchmarking of run-time environment is required to prove that these environments can be considered for the development of real-time applications. In this paper, a benchmarking framework is described and it is used to analyze the performance of an IEC 61499 run-time environment that is based on the real-time java Specification. The recently released IBM and Sun RTSJ implementations are used to demonstrate the effectiveness of the RTSJ based framework. Performance results prove the applicability of the proposed run-time environment and the model driven approach that was adopted, in the control and automation domain.

关键词： IEC 61499 Function Block real-time java RTSJ run-time environment performance analysis benchmark

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Safety-Critical java for Low-End Embedded Platforms 12

Safety-Critical Java for Low-End Embedded Platforms

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

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

ISBN: (纸本)9781450316880

We present an implementation of the Safety-Critical java profile (SCJ), targeted for low-end embedded platforms with as little as 16 kB RAM and 256 kB flash. The distinctive features of the implementation are a combination of a lean java virtual machine (HVM), with a bare metal kernel implementing hardware objects, first level interrupt handlers, and native variables, and an infrastructure written in java which is minimized through program specialization. The HVM allows the implementation to be easily ported to embedded platforms which have a C compiler as part of the development environment;the bare metal approach eliminates the need for a resource consuming operating system or C-library;the program specialization means that the infrastructure for the SCJ profile is optimized for a particular application keeping only the code and data the application needs. The SCJ implementation is evaluated with a known benchmark and shown to reduce this to a size where it can execute on a minimal configuration.

关键词： Embedded Systems real-time java Virtual Machine Safety-Critical java

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Patterns for Safety-Critical java Memory Usage 12

Patterns for Safety-Critical Java Memory Usage

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

作者： Rios, Juan Ricardo Nilsen, Kelvin Schoeberl, Martin Tech Univ Denmark Dept Informat & Math Modeling Lyngby Denmark San Diego Inc San Diego CA USA Tech Univ Denmark Dept Informat & Math Modeling Lyngby Denmark

ISBN: (纸本)9781450316880

Scoped memories are introduced in real-time java profiles in order to make object allocation and deallocation time and space predictable. However, explicit scoping requires care from programmers when dealing with temporary objects, passing scope-allocated objects as arguments to methods, and returning scope-allocated objects from methods. To simplify the correct usage of scopes, programming patterns may be helpful. We present patterns for simple subroutines, sequences of subroutine calls, and nested calls, where the patterns avoid memory leaks and unnecessary copying of values. The patterns are illustrated by implementations in the safety-critical java profile.

关键词： real-time systems real-time java safety-critical systems

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Using CHARTER tools to develop a Safety-Critical Avionics Application in java 12

Using CHARTER tools to develop a Safety-Critical Avionics Ap...

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

作者： Wedzinga, G. Wiegmink, K. Natl Aerosp Lab NLR Anthony Fokkerweg 2 NL-1059 CM Amsterdam Netherlands Natl Aerosp Lab NLR NL-8316 PR Marknesse Netherlands

ISBN: (纸本)9781450316880

Safety-critical digital avionics systems are becoming increasingly complex. Consequently, exhaustive testing may be impossible or impractical to demonstrate that the software of these systems complies with airworthiness requirements. Software development assurance in accordance with prescribed development standards is an accepted approach, but increases cost. These issues are addressed by the EU ARTEMIS CHARTER project. Its goals include managing system complexity, improving software quality, and reducing the total development effort. These goals have been achieved by a Quality Embedded Development (QED) approach, in which model-based development and real-time java are the key technologies. Tools have been developed to support development and verification activities. This paper presents CHARTER'S QED approach by taking examples from the development of a demonstrator for a safety-critical avionics system based on an aircraft Environmental Control System. The QED approach is assessed by comparing metrics that have been collected during the demonstrator development with metrics for conventional development. An important metric is the total development effort. The results indicate that a productivity improvement is achievable.

关键词： Safety Critical Avionics Systems Software Life-Cycle real-time java java Modeling Language Code Generation Formal Verification Resource Analysis Test Case Generation

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