Distributing RePast agent‐based simulations with HLA

Large, experimental multi‐agent system (MAS) simulations are highly demanding tasks, both computationally and developmentally. Agent toolkits provide reliable templates for the design of even the largest MAS simulations, without offering a solution to computational limitations. Conversely, distributed simulation architectures offer performance benefits, but the introduction of parallel logic can complicate the design process significantly. The motivations of distribution are not limited to this question of processing power. True interoperation of sequential agent‐simulation platforms would allow agents designed using different toolkits to transparently interact in common abstract domains. This paper discusses the design and implementation of a system capable of harnessing the computational power of a distributed simulation infrastructure with the design efficiency of an agent toolkit. The system permits integration, through a higher‐level architecture (HLA) federation, of multiple instances of the Java‐based lightweight agent‐simulation toolkit RePast. This paper defines abstractly the engineering process necessary in creating such middleware, and reports on the experience in the specific case of the RePast toolkit. The paper also presents performance results that illustrate that significant speedup can be achieved through the integration of RePast with HLA. Copyright © 2008 John Wiley & Sons, Ltd.     

基于多Agent的井下逃生仿真模型

利用基于多Agent的建模仿真方法对井下工作人员在遭遇瓦斯爆炸时如何逃生进行研究,采用基于Java的Eclipse开发平台和RePast建模仿真软件构建模型的运行平台,建立了基于多Agent的井下逃生仿真模型。模型仿真井下瓦斯爆炸时矿工的逃生过程。结果表明,利用这一模型能够较好地实现逃生仿真。     

面向Java 3D的CAD模型简化与转换

三维图形仿真的一个重要工作就是建立三维模型,若使用已有的模型可以节省一定的时间.文中主要讨论了如何将复杂的CAD模型应用于Java3D建立的图形仿真系统中.首先,对已有的Pro/E模型进行简化,以VRML格式导出,有两种方式应用于Java3D中.一种是直接编辑Pro/E模型导出的VRML格式文件,组织模型之间的链接关系;另一种是将Pro/E模型导出的VRML格式文件导入到3DMax中组织链接关系,然后导出为单一文件.最后联合使用这两种方式将一个复杂的空间机器人模型导入到Java3D,提高了图形数据的重用性和开发的快速性,经实践验证效果理想.     

A Toolkit for Generating Sentences from Context-Free Grammars

Producing sentences from a grammar, according to various criteria, is required in many applications. It is also a basic building block for grammar engineering. This paper presents a toolkit for context-free grammars, which mainly consists of several algorithms for sentence generation or enumeration and for coverage analysis for context-free grammars. The toolkit deals with general context-free grammars. Besides providing implementations of algorithms, the toolkit also provides a simple graphical user interface, through which the user can use the toolkit directly. The toolkit is implemented in Java and is available at http://lcs.ios.ac.cn/~zhiwu/toolkit.php. In the paper, the overview of the toolkit and the major algorithms implemented in the toolkit are presented, and experimental results and preliminary applications of the toolkit are also contained.     

A toolkit for efficient numerical applications in Java

Java is widely recognized as a good object-oriented programming language. However, it is often considered as too slow for numerically intensive applications. This paper presents a software toolkit that brings the computational efficiency of numerical Fortran libraries to Java. The toolkit is organized in two layers. In the first layer, Java wrappers provide access to numerical libraries like BLAS, LAPACK or NAG. The second layer comprises vector and matrix classes as well as classes for common linear algebra tasks. Numerical experiments show that this strategy can substantially improve the performance of Java-based numerical applications.     

GridSim仿真代码自动生成器GridsimHelper

基于离散事件仿真平台si叼ava的网格建模和仿真工具C}irdSim提供了大量用于仿真分布式系统的基础类。但是使用该工具进行仿真并不简单。除了编制大量代码之外,初学者还需要花费较长时间熟悉实验构造过程和各种基础类的使用方法。针对此问题,设计、实现了图形界面(Graphical User Interface, GUI)的仿真代码生成器GridSimHclpcr,旨在缩短GridSim平台的学习过程,减轻用户实施仿真实验的工作量。该工具允许用户对自行设计的调度算法进行仿真测试,并提供静态启发式算法min-min和max-min作为性能比较的对象。详细介绍了GridSim-Helper的设计思路和实现细节。仿真实验结果证实了该工具的正确性和有效性。     

基于VTK的CFD数据可视化Grid Service设计和实现

应用可视化工具VTK和Java在网格计算环境下实现了一个用于CFD数据后处理的高效率、易扩展、实用的可视化网格服务。网格服务接口用Web服务语言(WSDL)描述,网格服务内部实现使用VTK作为可视化内核,构建网格环境的中问件系统使用的是基于OGSA的GT3。实验结果表明,可视化网格服务可以充分利用远程强大计算资源,为性能较弱的客户端提供强大的可视化处理能力。     

Animation toolkit based on a database approach for reusing motions and models

As animations become more readily available, simultaneously the complexity of creating animations has also increased. In this paper, we address the issue by describing an animation toolkit based on a database approach for reusing geometric animation models and their motion sequences. The aim of our approach is to create a framework aimed for novice animators. Here, we use an alternative notion of a VRML scene graph to describe a geometric model, specifically intended for reuse. We represent this scene graph model as a relational database. A set of spatial, temporal, and motion operations are then used to manipulate the models and motions in an animation database. Spatial operations help in inserting/deleting geometric models in a new animation scene. Temporal and motion operations help in generating animation sequences in a variety of ways. For instance, motion information of one geometric model can be applied to another model or a motion sequence can be retargeted to meet additional constraints (e.g., wiping action on a table can be retargeted with constraints that reduce the size of the table). We present the design and implementation of this toolkit along with several interesting examples of animation sequences that can be generated using this toolkit.     

SwingStates: adding state machines to Java and the Swing toolkit

This article describes SwingStates, a Java toolkit designed to facilitate the development of graphical user interfaces and bring advanced interaction techniques to the Java platform. SwingStates is based on the use of finite‐state machines specified directly in Java to describe the behavior of interactive systems. State machines can be used to redefine the behavior of existing Swing widgets or, in combination with a new canvas widget that features a rich graphical model, to create brand new widgets. SwingStates also supports arbitrary input devices to implement novel interaction techniques based, for example, on bi‐manual or pressure‐sensitive input. We have used SwingStates in several Master's‐level classes over the past two years and have developed a benchmark approach to evaluate the toolkit in this context. The results demonstrate that SwingStates can be used by non‐expert developers with little training to successfully implement advanced interaction techniques. Copyright © 2007 John Wiley & Sons, Ltd.     

A model‐based development approach for the verification of real‐time Java code

Many real‐time systems are safety‐and security‐critical systems and, as a result, tools and techniques for verifying them are extremely important. Simulation and testing such systems can be exceedingly time‐consuming and these techniques provide only probabilistic measures of correctness. There are a number of model‐checking tools for real‐time systems. Although they provide formal verification for models, we still need to implement these models. To increase the confidence in real‐time programs written in real‐time Java, this paper proposes a model‐based approach to the development of such programs. First, models can be mechanically verified, to check whether they satisfy particular properties, by using current real‐time model‐checking tools. Then, programs can be derived from the model by following a systematic approach. We introduce a timed automata to RTSJ Tool (TART), a prototype tool to automatically generate real‐time Java code from the model. Finally, we show the applicability of our approach by means of four examples: a gear controller, an audio/video protocol, a producer/consumer and the Fischer protocol. Copyright © 2011 John Wiley & Sons, Ltd.     

基于XML的代理关键字处理方法

代理关键字被普遍应用于数据仓库的构建。在XML Schema映射为数据仓库结构的情况下,该文提出一种引入代理关键字的处理方法,利用Java工具包,将XML Schema转换成XOM树结构,在转换成关系模式时加入代理关键字,实现了XML文档与数据仓库间的直接转换。实验结果证明了该算法的有效性。     

基于swarm仿真平台的合同网协议的应用分析

以仿真软件为基础,实现一种高层通讯协议即合同网协议.首先解释了swarm在人工世界环境下进行计算机仿真模拟的基本思想.及swarm的主要概念和系统结构.进而利用Swarm进行仿真建模的一般思路,以具体实例"捕食者-猎物"问题为实验背景,以Java语言为二次开发语言,通过调用Swarm提供的各种类库,按合同网协议规范来设计"捕食者"之间的协作,并对问题的各个参数进行设置,建立了基于Swarm的研究合同网协议的仿真模型,仿真结果表明Swarm平台很适合基于多Agent的协作的仿真建模,以及发现了传统合同网的不足.     

Weakest pre-condition reasoning for Java programs with JML annotations

This paper distinguishes several different approaches to organising a weakest pre-condition (WP) calculus in a theorem prover. The implementation of two of these approaches for Java within the LOOP project is described. This involves the WP-infrastructures in the higher order logic of the theorem prover PVS, together with associated rules and strategies for automatically proving JML specifications for Java implementations. The soundness of all WP-rules has been proven on the basis of the underlying Java semantics. These WP-calculi are integrated with the existing Hoare logic, and together form a verification toolkit in PVS: typically one uses Hoare logic rules to break a large verification task up into smaller parts that can be handled automatically by one of the WP-strategies.     

基于Web模式的医学图像三维重建与切割*

基于VTK开源软件包,结合Java applet编程,采用Java applet签名技术对程序进行签名认证。实现了Web方式下DICOM医学图像的三维重建,在重建的三维体上清晰显示出了人体器官的解剖结构,重建可在Internet上以Web模式跨平台运行,并可在三维体上进行交互切割和模拟手术开窗。分析用Java applet实现基于Web的医学断层图像三维重建是可行的,且实现的系统便于维护和升级,说明在临床上有很大应用价值。     

Estimation of dynamical characteristics of a parallel program on a model

This paper considers a model of a parallel program that can efficiently be interpreted on an instrumental computer, providing a means for a sufficiently accurate prediction of the actual time needed for execution of the parallel program on a given parallel computational system. The model is designed for parallel programs with explicit message passing written in Java with calls to the MPI library and is a part of the ParJava environment. The model is obtained by transforming the program control tree, which, for Java programs, can be constructed by modifying the abstract syntax tree. The communication functions are simulated on the basis of the LogGP model, which makes it possible to take into account specific features of the distributed computational system.     

A workflow management system based on intelligent collaborative objects

This paper describes an architecture for workflow management systems based on Workflow Intelligent Business Objects (WIBOs). The design of WIBOs is based on principles of intelligence, autonomy, collaboration and co-operation. Using WIBOs that carry out tasks on users’ behalf, it is possible to build workflow systems that bring further improvements in process automation and dynamic management, and achieve dynamic (re)allocation of resources to Actors. A WIBO prototype architecture has been implemented using Java. A Java Remote Method Invocation (RMI) has been used to enable WIBOs to communicate over an Intranet or Internet.     

MobileRMI: upgrading Java Remote Method Invocation towards mobility

Code mobility is recognized as a promising design technique, able to improve flexibility, adaptability and bandwidth utilization in mobile computing applications. To promote and facilitate its use, researchers argue that code mobility should be made available to programmers in combination with, and not as an alternative to, more traditional programming models. This paper describes the design and implementation of the MobileRMI toolkit which, unlike agent-based systems, enables mobility-based programming within a widely accepted middleware platform, Java Remote Method Invocation (RMI). Our toolkit provides a set of mobility primitives that allow programmers to create, clone and move remote objects across a network. To preserve location transparency we implemented a novel, efficient scheme for automatically updating remote references by exploiting the distributed garbage collector. Programming examples are given and a case study where an adaptive application uses logical mobility to minimize communication over a mobile ad hoc network is presented. Experience from using MobileRMI confirmed the benefit of designing both static and mobile applications within the same programming framework. Copyright © 2005 John Wiley & Sons, Ltd.     

A portable AWT/Swing architecture for Java game development

Recently, the performance of Java platforms has been greatly improved to satisfy the requirements for game development. However, the rendering performance of Java 1.1, which is still used by about one‐third of current Web browser users, is not sufficient for high‐profile games. Therefore, practically, Java game developers, especially those who use applets, have to take this into consideration in most environments. In order to solve the above problems, this paper proposes a portable window toolkit architecture called the CYC Window Toolkit (CWT) with the ability to: (1) reach high rendering performance particularly in Java 1.1 applications and applets when using DirectX to render widgets in CWT; (2) support AWT/Swing compatible widgets, so hence the CWT can be easily applied to existing Java games; (3) define a general architecture that supports multiple graphics libraries such as AWT, DirectX and OpenGL, multiple virtual machines such as Java VM and .NET CLR, and multiple operating systems (OSs) such as Microsoft Windows, Mac OS and UNIX‐based OSs; (4) provide programmers with one‐to‐one mapping APIs to directly manipulate DirectX objects and other game‐related properties. The CWT has also been applied to an online Java game system to demonstrate the proposed architecture. Copyright © 2006 John Wiley & Sons, Ltd.     

Formally based semi-automatic implementation of an open security protocol

This paper presents an experiment in which an implementation of the client side of the SSH Transport Layer Protocol (SSH-TLP) was semi-automatically derived according to a model-driven development paradigm that leverages formal methods in order to obtain high correctness assurance. The approach used in the experiment starts with the formalization of the protocol at an abstract level. This model is then formally proved to fulfill the desired secrecy and authentication properties by using the ProVerif prover. Finally, a sound Java implementation is semi-automatically derived from the verified model using an enhanced version of the Spi2Java framework. The resulting implementation correctly interoperates with third party servers, and its execution time is comparable with that of other manually developed Java SSH-TLP client implementations. This case study demonstrates that the adopted model-driven approach is viable even for a real security protocol, despite the complexity of the models needed in order to achieve an interoperable implementation.