VyrdMC: Driving Runtime Refinement Checking with Model Checkers

This paper presents VyrdMC, a runtime verification tool we are building for concurrent software components. The correctness criterion checked by VyrdMC is refinement: Each execution of the implementation must be consistent with an atomic execution of the specification. VyrdMC combines testing, model checking, and Vyrd, the runtime refinement checker we developed earlier. A test harness first drives the component to a non-trivial state which serves as the starting state for a number of simple, very small multi-threaded test cases. An execution-based model checker explores for each test case all distinct thread interleavings while Vyrd monitors executions for refinement violations. This combined approach has the advantage of improving the coverage of runtime refinement checking at modest additional computational cost, since model checkers are only used to explore thread interleavings of a small, fixed test program. The visibility and detailed checking offered by using refinement as the correctness criterion differentiate our approach from simply being a restricted application of model checking. An important side benefit is the reduction in program instrumentation made possible if VyrdMC is built using a model checker with its own virtual machine, such as Java PathFinder [Guillaume Brat, Klaus Havelund, Seung-Joon Park, and Willem Visser. Model Checking Programs. In IEEE International Conference on Automated Software Engineering (ASE), September 2000]. We are investigating the use of two different model checkers for building VyrdMC: Java PathFinder, an explicit-state model checker and Verisoft, a “stateless” model checker [P. Godefroid. Model Checking for Programming Languages using VeriSoft. In Proceedings of the 24th ACM Symposium on Principles of Programming Languages, pages 174–186, Paris, January 1997].     

Java与ActiveX的安全模型

本文首先介绍了有关可移动代码安全性的几种基本模型，然后对比讨论了Java与ActiveX的安全机制，及其各自存在的问题。     

The Back-End of a Two-Layer Model for a Federated National Datastore for Academic Research VOs that Integrates EGEE Data Management

This paper proposes an architecture for the back-end of a federated national datastore for use by academic research communities, developed by the e-INIS (Irish National e-InfraStructure) project, and describes in detail one member of the federation, the regional datastore at Trinity College Dublin. It builds upon existing infrastructure and services, including Grid-Ireland, the National Grid Initiative and EGEE, Europe’s leading Grid infrastructure. It assumes users are in distinct research communities and that their data access patterns can be described via two properties, denoted as mutability and frequency-of-access. The architecture is for a back-end—individual academic communities are best qualified to define their own front-end services and user interfaces. The proposal is designed to facilitate front-end development by placing minimal restrictions on how the front-end is implemented and on the internal community security policies. The proposal also seeks to ensure that the communities are insulated from the back-end and from each other in order to ensure quality of service and to decouple their front-end implementation from site-specific back-end implementations.     

J0sML--一个用于实现Java对象序列化的XML模型

在介绍Java对象序列化的概念及用XML实现序列化的工作过程的基础上，提出了一个实现Java对象序列化的XML模型JosML。     

Java 3D—Java语言的三维图形解决方案

Java 3D是一种新型的三维图形编程方案,结合Java语言,在开发Internet及WWW上的三维图形网络应用有极大优势。本文介绍了Java3D API的特点,并结合一个利用Java 3D开发的实例说明其结构与编程模式。     

JnetMVC—一个新的Java网络编程MVC模型

在有杉Java的网络编程机制（RMI,Socket通信,Servlet等）开发软件时,为了提高对象的再利用率,使系统具有更好的柔软性,以MVC模型为基础,提出一个Java网络编程新模型JnetMVC。     

端口-连接型产品配置知识的Java表达

扩展UML语言可以表达端口一连接型产品的配置知识．把UML表达知识转换为Java形式,转换后的Java知识库保持了UML表达知识的易读、易于人工修改、易于重用等优点．     

Decentralized Motion Planning for Multiple Mobile Robots: The Cocktail Party Model

This paper presents an approach for decentralized real-time motion planning for multiple mobile robots operating in a common 2-dimensional environment with unknown stationary obstacles. In our model, a robot can see (sense) the surrounding objects. It knows its current and its target's position, is able to distinguish a robot from an obstacle, and can assess the instantaneous motion of another robot. Other than this, a robot has no knowledge about the scene or of the paths and objectives of other robots. There is no mutual communication among the robots; no constraints are imposed on the paths or shapes of robots and obstacles. Each robot plans its path toward its target dynamically, based on its current position and the sensory feedback; only the translation component is considered for the planning purposes. With this model, it is clear that no provable motion planning strategy can be designed (a simple example with a dead-lock is discussed); this naturally points to heuristic algorithms. The suggested strategy is based on maze-searching techniques. Computer simulation results are provided that demonstrate good performance and a remarkable robustness of the algorithm (meaning by this a virtual impossibility to create a dead-lock in a random scene).     

The real-time specification for Java

New languages, programming disciplines, operating systems, and software engineering techniques sometimes hold considerable potential for real-time software developers. A promising area of interest-but one fairly new to the real-time community-is object-oriented programming. Java, for example, draws heavily from object orientation and is highly suitable for extension to real-time and embedded systems. Recognizing this fit between Java and real-time software development, the Real-Time for Java Experts Group (RTJEG) began developing the real-time specification for Java (RTSJ) in March 1999 under the Java Community Process. This article explains RTSJ's features and the thinking behind the specification's design. The goal of the RTJEG, of which the authors are both members, was to provide a platform-a Java execution environment and application program interface (API)-that lets programmers correctly reason about the temporal behavior of executing software     

层次型Java软件质量度量模型研究

软件度量研究方兴未艾,构建软件度量模型是其中一个重要的研究方向。度量模型从本质上说,是一组对软件进行评价的标准。这个标准并不是仅仅为了用来证明软件的好坏优劣,也用来反映不同软件系统或者软件模块的特点,从而为不同的需求服务。计算机科学中没有绝对的概念,它从诞生起就是紧密围绕应用服务的,计算机科学的研究一定要和现实需求相关联,因此作为一种评价标准,度量模型同样是从不同方面来综合评测软件的属性,从而在不同需求面前提供可参考的选择。     

基于Java的多层分布式应用模型研究

分析了JDBC和RMI技术的基础上,详细介绍了基于Java的多层分布式应用系统体系结构及其实现技术,并给出了一个基于Java技术的多层分布式应用系统解决方案。     

基于Java的对象模型消息机制实现

Java语言标准不提供消息,使得面向对象模型中消息机制的实现十分不便。针对上述问题,利用Java的接口、继承及多态机制,实现一种风格与微软基础类库中framework的消息机制相似的对象模型消息机制,将其应用于一款基于LEGO机器人的协同式智能化多机器人系统,结果证明该消息机制具有合理性、有效性和易实现性。     

Java3D API与Java3D编程技术

Ｊａｖａ３Ｄ ＡＰＩ是应用于３Ｄ图形编程的Ｊａｖａ类包,本文具体介绍Ｊａｖａ３Ｄ ＡＰＩ中主要类的使用,Ｊａｖａ３Ｄ编程模式和显示模式,阐明了Ｊａｖａ３Ｄ编程的思路和方法。     

JSetL: a Java library for supporting declarative programming in Java

In this paper we present a Java library—called JSetL—that offers a number of facilities to support declarative programming such as those usually found in logic or functional declarative languages: logical variables, list and set data structures (possibly partially specified), unification and constraint solving over sets, non‐determinism. The paper describes the main features of JSetL and it shows, through a number of simple examples, how these features can be exploited to support a real declarative programming style in Java. Copyright © 2006 John Wiley & Sons, Ltd.     

面向多业务通信调度的优先级排队模型研究

互联网业务的快速发展为数据的高效传输提出了挑战,需要一种有效的数据包调度方案来满足各项业务的 QoS需求。基于数据包的时延敏感性、长度等属性,采用优先级排队模型研究各种调度策略的性能,指出非抢占式短 包优先策略能提供最小的总体时延;在此基础上对时延敏感业务和非时延敏感业务采用不同的策略,设计最优化传输 性能的业务调度多优先级排队模型o NS-2平台下的仿真实验证明了所提模型的优越性,并演示了不同流量下的数据 包排队特性,以及包交付率、吞吐量、时延等指标的变化规律,从而为性能的优化提供了参照。     

一种实用的磨矿多模型预测控制策略研究

房矿过程是选矿过程中的重要一环,属多输入多输出系统,并存在严重的扰动变量(诸如硬度等)和时变参数.介绍了一种磨矿控制系统中实用的多变量动态矩阵控制的多模型控制策略.该方法基于不同的矿石硬度对球磨过程建立不同的阶跃模型进行多模型预测控制.仿真证实了该方法的有效性.     

多线程Java程序安全行为模型的静态检查方法

多线程作为支持程序结构化和并行化的重要机制,其应用越来越广泛,多线程应用程序的安全性也成为新的研究热点之一.针对Java多线程程序,文中采用参数化扩展上下文无关文法作为其安全相关行为模型的抽象表示,给出了从多线程Java程序自动生成安全相关行为模型的方法,形式地描述了静态检查该模型是否满足安全策略的实现,并应用到携带模型代码方法的实现框架中.该方法为安全执行非信任多线程Java移动代码提供了有效支持.     

Java: Internet的面向对象语言

本文介绍了Ｊａｖａ的语言基础、面向对象技术、目标代码结构无关技术、稳定性和安全性技术、线程支持机制、网络通讯技术、异常处理和Ｊａｖａａｐｐｌｅｔ的概念，最后讨论了它的不足和一些个人观点     

Multiple Model Q-Learning for Stochastic Asynchronous Rewards

This paper investigates reinforcement learning problems where a stochastic time delay is present in the reinforcement signal, but the delay is unknown to the learning agent. This work posits that the agent may receive individual reinforcements out of order, which is a relaxation of an important assumption in previous works from the literature. To that end, a stochastic time delay is introduced into a mobile robot line-following application. The main contribution of this work is to provide a novel stochastic approximation algorithm, which is an extension of Q-learning, for the time-delayed reinforcement problem. The paper includes a proof of convergence as well as grid world simulation results from MATLAB, results of line-following simulations within the Cyberbotics Webots mobile robot simulator, and finally, experimental results using an e-Puck mobile robot to follow a real track despite the presence of large, stochastic time delays in its reinforcement signal.