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作者： Miguel Arnaldo Ayala Naval Postgraduate School

学位级别：硕士

Autonomous underwater vehicles (AUVs) have a great potential use for the United States Marine Corps and United States Navy. When performing amphibious operations, underwater mines present a danger for t he forces going ashore. The use of underwater vehicles for the detection of this mines and signaling to the Amphibious Ready Group is very attractive. With advancements in hardware and object oriented language technology, more complicated and robust software can be developed. The Naval Postgraduate School Center for AUV Research has been designing, building, operating, and researching AUVs since 1987. Each generation of vehicles has provided substantially increased in operational capabilities and level of sophistication in the hardware and software respectively. With the advancement in real-time computer languages support, object oriented technology, and cost efficient and high performance hardware, this thesis lays the foundations to develop a software system for the execution level using the java language. We look into the java real-time specifications and extension to familiarize with the capabilities of java for real-time support, and study java boards and its application for embedded real-time systems. We developed an object-oriented design for the execution level control software and implemented the design in java. A testing phase is still under work.

关键词： Software Engineering Autonomous Underwater Vehicles AUV java java Board Embedded java real-time Software real-time java UML

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Region-Based RTSJ Memory Management: State of the art

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SCIENCE OF COMPUTER PROGRAMMING 2012年第5期77卷 644-659页

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

Developing a real-time system in java requires awareness of memory behaviour in addition to software functional requirements. The real-time Specification for java (RTSJ) introduces a scoped memory model to avoid garbage collection delays in critical real-time applications which need to meet hard real-time constraints. Scoped memory management has certain advantages over garbage collection in terms of predictability. However, developing a real-time application using scoped memory areas (regions) may suffer from both design and runtime errors. Moreover, from a memory footprint perspective, the inability to determine precisely how many scoped memory areas should be used and which objects or threads should be allocated into these scoped memory areas makes using RTSJ problematic for developing real-time systems. In this paper, a survey of the current approaches to improve scoped memory management and new emerging challenges in RTSJ scoped memory management model are presented. Categorizing those problems and challenges provides a picture of the issues researchers have yet to investigate and to support solutions for an optimal scoped memory model. Current approaches and a set of benchmarks used to evaluate current solutions are presented and new research questions in developing realtime java systems using a scoped memory model are proposed. (C) 2012 Elsevier B.V. All rights reserved.

关键词： RTSJ memory management Scoped memory Immortal memory Memory regions real-time java Benchmarks Programming languages

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Simple Multiplexing Headers for the JRMP Stream Subprotocol

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IEEE LATIN AMERICA TRANSACTIONS 2016年第2期14卷 1005-1010页

作者： Basanta, P. Garcia, M. Univ Carlos III Madrid E-28903 Getafe Leganes Spain

This article deals with a simple optimization for a level-5 protocol called JRMP (java's Remote Method Protocol), which is used in a distribution model named java's RMI (java's Remote Method Invocation). The main JRMP subprotocol, namely Stream, has been enhanced with a simple and direct multiplexing mechanism that offers the possibility of transferring several parallel request-response interactions without opening new TCP/IP connections. The overhead required to process headers and the advantages stemmed from the approach in terms of response-time are explored on a switched-ethernet benchmark application.

关键词： Protocol implementation empirical evaluation JRMP 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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Implicit ownership types for memory management

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SCIENCE OF COMPUTER PROGRAMMING 2008年第3期71卷 213-241页

作者： Zhao, Tian Baker, Jason Hunt, James Noble, James Vitek, Jan Univ Wisconsin Milwaukee WI 53201 USA Alcas GmbH Karlsruhe Germany Victoria Univ Wellington New Zealand Purdue Univ W Lafayette IN 47907 USA

The real-time Specification for java (RTSJ) introduced a range of language features for explicit memory management. While the RTSJ gives programmers fine control over memory use and allows linear allocation and constant-time deallocation, the RTSJ relies upon dynamic runtime checks for safety, making it unsuitable for safety critical applications. We introduce ScopeJ, a statically-typed, multi-threaded, object calculus in which scopes are first class constructs. Scopes reify allocation contexts and provide a safe alternative to automatic memory management. Safety follows from the use of an ownership type system that enforces a topology on run-time patterns of references. ScopeJ's type system is novel in that ownership annotations are implicit. This substantially reduces the burden for developers and increases the likelihood of adoption. The notion of implicit ownership is particularly appealing when combined with pluggable type systems, as one can apply different type constraints to different components of an application depending on the requirements without changing the source language. In related work we have demonstrated the usefulness of our approach in the context of highly-responsive systems and stream processing. Published by Elsevier B.V.

关键词： real-time java RTSJ type systems memory management ownership types

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Scheduling of hard real-time garbage collection

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real-time SYSTEMS 2010年第3期45卷 176-213页

作者： Schoeberl, Martin Vienna Univ Technol Inst Comp Engn A-1040 Vienna Austria

Automatic memory management or garbage collection greatly simplifies development of large systems. However, garbage collection is usually not used in real-time systems due to the unpredictable temporal behavior of current implementations of a garbage collector. In this paper we propose a real-time garbage collector that can be scheduled like a normal real-time thread with a deadline monotonic assigned priority. We provide an upper bound for the collector period so that the application threads will never run out of memory. Furthermore, we show that the restricted execution model of the Safety Critical java standard simplifies root scanning and reduces copying of static data. Our proposal has been implemented and evaluated in the context of the java processor JOP.

关键词： real-time systems Garbage collection real-time java

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Introduction to the Special Issue: JTRES 2009

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2011年第14期23卷 1607-1608页

作者： Schoeberl, Martin Teresa Higuera-Toledano, M. Tech Univ Denmark Dept Informat & Math Modeling Lyngby Denmark Univ Complutense Madrid E-28040 Madrid Spain

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Towards highly configurable real-time object request brokers 5

Towards highly configurable real-time object request brokers

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5th IEEE International Symposium on Object-Oriented real-time Distributed Computing (ISORC 2002)

作者： Klefstad, R Schmidt, DC O'Ryan, C Univ Calif Irvine Dept Elect & Comp Engn Irvine CA 92697 USA

ISBN: (纸本)0769515584

This paper discusses the software architecture of a real-time CORBA object request broker (ORB) called ZEN, written in real-time java, which is designed to eliminate common sources of overhead and non-determinism in ORB implementations. We illustrate how ZEN can be configured to select the minimal set of components used by an application. Our experience with ZEN indicates that combining real-time java with real-time CORBA is a major step forward towards simplifying the development and maintenance of distributed middleware and applications with stringent quality of service requirements.

关键词： distributed real-time and embedded systems real-time CORBA real-time java

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Addressing dynamic dispatching issues in WCET analysis for object-oriented hard real-time systems 5

Addressing dynamic dispatching issues in WCET analysis for o...

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5th IEEE International Symposium on Object-Oriented real-time Distributed Computing (ISORC 2002)

作者： Hu, EYS Bernat, G Wellings, A Univ York Dept Comp Sci Real Time Syst Res Grp York YO10 5DD N Yorkshire England

ISBN: (纸本)0769515584

There is a trend towards using object-oriented-programming languages to develop hard real-time applications. However, some object-oriented-features, such as dynamic dispatching and dynamic loading, are prohibited from being used in hard real-time systems because they are either unpredictable and/or unanalysable. Arguably, these restrictions could make applications very limited and unrealistic since they could eliminate the major advantages of object-oriented programming. This paper demonstrates how we can address the dynamic dispatching issues in Worst-Case Execution Timing (WCET) analysis with minimum annotations. The major contributions include: discussing the major issues involved in using and restricting dynamic binding features;weakening the restriction of using dynamic dispatching;presenting how to estimate tighter and safer WCET value in object-oriented hard real-time systems. Our approach shows that allowing the use of dynamic dispatching can not only provide a more flexible way to develop object-oriented hard real-time applications, but also does not necessarily result in unpredictable timing analysis.

关键词： java hard real-time systems real-time java worst-case execution time (WCET) analysis objectoriented WCET dynamic dispatching

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A Dynamic Memory Management Unit for real time Systems 20

A Dynamic Memory Management Unit for Real Time Systems

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20th IEEE International Symposium on real-time Distributed Computing (ISORC)

作者： Harvey-Lees-Green, Nicholas Biglari-Abhari, Morteza Malik, Avinash Salcic, Zoran Univ Auckland Elect & Comp Engn Auckland New Zealand

ISBN: (纸本)9781538615744

time predictability is a first class requirement in safety critical system design. Techniques exist for the timing analysis of programs designed in memory managed languages, but these require detailed knowledge of memory allocation. Moreover, enforcing hard real-time guarantees for systems designed in such garbage collected languages is difficult, because of the so called collection pause - however incremental. This paper proposes a novel solution whereby a separate reference counting unit replaces the garbage collector. We present the underlying concepts of the Reference Counting Memory Management Unit (RCMMU) and its use for garbage collection. In addition, we present an implementation that includes a specialized memory arrangement that allows for object management transactions to occur concurrently with program execution, with no resultant impact upon program performance. The RCMMU has been targeted for use with java but can be adopted to be used with other memory managed languages. The hardware-implemented RCMMU removes all overhead associated with garbage collection operations when compared against a software-only collector. Additionally, it simplifies the static worst-case execution time analysis of programs.

关键词： Garbage collection real-time java real-time systems embedded systems FPGA memory memory allocation safety critical systems time predictability

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