一种实时Java处理器的指令存取部件设计与实现

Java语言目前被广泛应用于各个领域。然而在嵌入式实时应用领域,Java由于其固有的执行速度缺陷往往达不到应用的标准。为了解决这一问题,设计一种支持Java的处理器成为提高Java实时性的一种可靠途径。由于Java虚拟机目前采用的是基于堆栈的实现方式,因而处理器的存储体系结构会出现一些与传统RISC处理器不同的特征。描述了一种Java实时处理的取指令存取部件设计方案,很好地符合了Java特有的体系结构。     

Java虚拟机的硬件实现研究

Java语言的平台无关性使其正在进入嵌入式系统领域，但Java的性能问题一直是Java应用关注的焦点。JIT技术的运用在一定程度上提高了Java的执行速度，但在对实时性要求高和存储受限的嵌入式等系统的运用中仍然难以满足其要求。文章提出了一种基于硬件的解决方法——Java处理器，它能直接执行Java字节码，从而提高Java的性能，以用于实时及嵌入式系统。     

一种实时JAVA处理器的数据通路研究

FPGA具有灵活性高、设计周期短、成本低、风险小等优势,因此现已成为芯片设计的热点.该文设计了一种能在FP-GA芯片中实现的32位Java处理器JPOR(Java Processor Optimized For RTSJ)的数据通路,可以对实时Java规范提供有效支持.提供一种嵌入式实时系统的Java平台,该处理器具有指令系统简洁,直接执行JAVA字节码,提供对线程调度和管理的硬件支持等优点.     

基于FPGA的Java处理器设计

针对Java技术在嵌入式领域的广泛应用,设计了一个适用于低端嵌入式设备的32位环境的Java处理器JPOR。该处理器由FPGA芯片实现,采用一种新的Java栈结构,指令系统简洁,可以直接执行Java字节码,能够对实时Java规范(RTSJ)提供有效支持。在Xilinx SPARTAN-3平台上通过了功能仿真,表明该Java处理器能够在低成本的FPGA芯片中实现。     

实时Java平台的类预处理器研究

设计并实现一种针对32 bit嵌入式实时Java平台的类预处理器,通过把标准class文件转换成适合Java处理器——Jpor32直接执行的内存映像,将在运行时动态装载和解析class的工作交由类预处理器提前完成,从而消除影响运行时实时性的一些操作,并降低Java处理器的设计复杂性。     

实时Java平台的类预处理器研究

设计并实现一种针对32 bit嵌入式实时Java平台的类预处理器,通过把标准class文件转换成适合Java处理器——Jpor32直接执行的内存映像,将在运行时动态装载和解析class的工作交由类预处理器提前完成,从而消除影响运行时实时性的一些操作,并降低Java处理器的设计复杂性。     

基于B/S结构的嵌入式实时监测系统研究

论述了一种使用ARM处理器构建的嵌入式Web远程测控终端,使用Java嵌入技术设计了其控制网页,用其构成的测控系统,仅需要监测端有可以接入Internet的IE浏览器,就能够实时显示终端采集到的信号波形并获取信号数据.这种新兴测控技术具有广泛的应用前景.     

基于RTSJ的嵌入式系统API的研究与应用

描述了一个基于RTSJ的应用程序接口,该API的功能是提供高级的并发实时计算结构,优化实时嵌入式系统开发.同时,部署和优化(在开销足迹/时间要求方面)实时J ava应用程序到一个指定的Java处理器上.本文借助于实现电梯控制系统,说明这些API的使用方法.     

关于嵌入式Java技术的研究

自从Sun公司提出Java技术以来,对Java的应用和研究一直呈逐渐上升的趋势,其范围涵盖超级计算、企业计算以及嵌入计算等领域,该文着重讨论了Sun提出的嵌入式Java规范及J2ME的相关技术,包括嵌入虚拟机的划分、实时机制以及无线应用等方面.     

J2ME在ARM-Linux嵌入式系统上的移植

Java技术在平台无关性、安全性、适应网络环境等方面具有优势,在嵌入式系统及消费类电子领域得到广泛应用。J2ME是一种针对嵌入式设备的Java运行平台。以phoneME这款开源的J2ME软件作为研究对象,给出ARM-Linux嵌入式系统上移植J2ME平台的方法,通过搭建交叉编译环境和相关基础配置,在S3C2410系统上移植并建立J2ME,为嵌入式系统上的Java应用开发提供平台。实验表明,本移植方案是可行的。     

基于Java多线程技术的网络编程

Java强大的安全性使得其在网络编程中被广泛采用,特别是其出色的多线程机制。利用Java的多线程编程接口,开发人员可以方便地写出支持多线程的应用程序,有效地减少并发并行程序设计的困难,提高了程序执行效率。以开发一个多用户具有并发服务器的网络聊天室为例,论述Java的多线程技术在网络编程中的应用。     

一种实时Java处理器''''区域''''内存实现模型

Java实时规范（RTSJ）提出的‘区域’内存（Scoped Memory）既避免了垃圾回收对系统实时性的影响，又能充分利用内存空间，引起了众多研究人员的重视．本文讨论了‘区域’内存的实现及影响最坏情况下执行时间（WCET）的因素，并提出一种针对嵌入式实时Java处理器的‘区域’内存实现模型．该模型中非实时处理在字节码被执行之前完成，消除了运行时管理‘区域’内存对WCET的影响，在简化处理器实现的同时保证了运行时WCET的可预测性．     

A multiplatform Java wrapper for the BioAPI framework

We present a solution for the development of multiplatform and web-oriented Java applications for biometric authentication based on the BioAPI framework. Our proposal is a single Java Native Interface wrapper that is compatible with the BioAPI instantiations of Windows and Linux/Unix operating systems. Following a study of existing wrappers, we extended the open-source Linux/Unix wrapper to include Windows support. In order to show the utility of this multiplatform Java wrapper, we discuss some of its possible uses and present a real-life application.     

利用缓冲区提高Java应用程序的I／O性能

Java语言的跨平台特性使得其在各个领域得到了广泛应用。与此同时，Java应用程序的性能，特别是I／O性能，也是人们普遍关注的话题。本文采用一个生物信息学应用程序的实例来探讨如何利用I／O缓冲区提高Java应用程序的I／O性能。我们采用三种不同的I／O缓冲区的实现方式来实现该应用程序，对其进行性能分析比较并将其与相应的C＋＋应用程序进行比较。大量实验表明，I／O缓冲区对于Java应用程序的I／O性能起着至关重要的作用。恰当地使用I／O缓冲区，某些场合下能使Java应用程序的I／O性能略高高于相应的C＋＋应用程序的I／O性能。     

Device level communication libraries for high‐performance computing in Java

Since its release, the Java programming language has attracted considerable attention from the high‐performance computing (HPC) community because of its portability, high programming productivity, and built‐in multithreading and networking support. As a consequence, several initiatives have been taken to develop a high‐performance Java message‐passing library to program distributed memory architectures, such as clusters. The performance of Java message‐passing applications relies heavily on the communications performance. Thus, the design and implementation of low‐level communication devices that support message‐passing libraries is an important research issue in Java for HPC. MPJ Express is our Java message‐passing implementation for developing high‐performance parallel Java applications. Its public release currently contains three communication devices: the first one is built using the Java New Input/Output (NIO) package for the TCP/IP; the second one is specifically designed for the Myrinet Express library on Myrinet; and the third one supports thread‐based shared memory communications. Although these devices have been successfully deployed in many production environments, previous performance evaluations of MPJ Express suggest that the buffering layer, tightly coupled with these devices, incurs a certain degree of copying overhead, which represents one of the main performance penalties. This paper presents a more efficient Java message‐passing communications device, based on Java Input/Output sockets, that avoids this buffering overhead. Moreover, this device implements several strategies, both in the communication protocol and in the HPC hardware support, which optimizes Java message‐passing communications. In order to evaluate its benefits, this paper analyzes the performance of this device comparatively with other Java and native message‐passing libraries on various high‐speed networks, such as Gigabit Ethernet, Scalable Coherent Interface, Myrinet, and InfiniBand, as well as on a shared memory multicore scenario. The reported communication overhead reduction encourages the upcoming incorporation of this device in MPJ Express ( http://mpj‐express.org ). Copyright © 2011 John Wiley & Sons, Ltd.     

Don't know beans? Try Java

It's hard to believe that Java has been around for just four short years (1996-2000). For several years, IT managers and system developers have been regarding Java with a watchful eye, waiting for the programming language to realize its much-vaunted potential. Today, with the explosion in e-commerce, Java is assuming an important role in front-end graphical user interfaces (GUIs), multitiered server applications, and mobile agents. Businesses are using Java in these applications because its platform independence, downloadability, and built-in security make it the implementation language of choice for online business applications. To better assess where Java fits into your organization's business systems, it's helpful to know how the language developed and where Java's developers are taking it     

基于CORBA和Java Servlet的多层分布式应用系统的实现

Servlet是Java技术在Web上的扩展,支持Web服务器的应用开发。本文介绍了Java Servlet的工作原理,并将CORBA分布式对象技术运用于异构平台中网络数据库应用的设计,提出了基于CORBA和Java Servlet的5层Web数据库应用体系结构,并给出了基于该体系结构的一个具体项目实例。     

Java for real-time

Java is a new programming language publicly released by Sun Microsystems in May of 1995 with hopes of revolutionizing the software industry. The popular press has responded with numerous articles touting the language's benefits. Since many of the applications which Java is intended to serve have real-time characteristics, we have recently undertaken to develop a set of standard extensions to provide Java programmers with the ability to describe the real-time requirements of their Java applications. This brief report summarizes the issues that have influenced the design of Real-Time Java and provides an overview of its current embodiment.     

Toward Automated Support for Transparent Interoperable Queries

Many Object-Oriented Databases (OODBs) use programming languages that predate Java, such as C++, CLOS and Smalltalk. Thus, there is a growing need for interoperating these OODBs with new applications that require Java. Unfortunately, there are few mechanisms that allow software developers to easily integrate Java applications with non-Java OODBs. Although various interoperability mechanisms have been developed over the years, these approaches have some significant drawbacks in practice. They are often difficult to use, provide little, if any, automated support, and produce software that is difficult to engineer and maintain. In this paper, we describe an interoperability approach that allows application developers to seamlessly and transparently access non-Java OODBs from Java applications. We first present JOQL, a Java-based object query language that we are developing. JOQL queries are embedded in Java applications and are used to perform queries over C++-based OODBs. We also describe an accompanying toolset that processes Java programs containing JOQL queries. The toolset produces all the necessary code allowing Java applications to access and manipulate a C++-based OODB. As a result, application developers are free to work in Java without having to concern themselves with the details of interoperating with C++. Finally, we provide some preliminary experimental data that demonstrates our approach incurs a reasonable performance overhead.