一种面向构件化软件的在线演化方法

针对构件化软件系统,提出了一种对软件进行在线演化的方案,并以一个符合J2EE规范的构件运行支撑平台为例讨论了该方案的实现.该方案借助JAVA平台的类装载机制,通过仔细划分构件实例的生命周期,针对不同状态的构件采取相应的措施,实现了以构件为粒度的软件在线演化.     

Special Feature the Intel 8089: An Integrated I/O Processor

As most mainframe manufacturers have demonstrated, the logical solution to I/O control problems is to deploy intelligent I/O subsystems. Intel's 8089 brings this capability to microcomputer systems.     

A Hint Frequency Based Approach to Enhancing the I/O Performance of Multilevel Cache Storage Systems

With the enormous and increasing user demand, I/O performance is one of the primary considerations to build a data center. Several new technologies in data centers, such as tiered storage, prompt the widespread usage of multilevel cache techniques. In these storage systems, the upper level storage typically serves as a cache for the lower level, which forms a distributed multilevel cache system. However, although many excellent multilevel cache algorithms have been proposed to improve the I/O performance, they still have potential to be enhanced by investigating the history information of hints. To address this challenge, in this paper, we propose a novel hint frequency based approach (HFA), to improve the overall multilevel cache performance of storage systems. The main idea of HFA is using hint frequencies (the total number of demotions/promotions by employing demote/promote hints) to efficiently explore the valuable history information of data blocks among multiple levels. HFA can be applied with several popular multilevel cache algorithms, such as Demote, Promote and Hint-K. Simulation results show that, compared with original multilevel cache algorithms such as Demote, Promote and Hint-K, HFA can improve the I/O performance by up to 20% under different I/O workloads.     

影响VoD服务器I/O性能的关键因素

在讨论了基于网络视频点系统模型和通用服务器体系结构的基础上,主要分析了影响视频点播服务器性能I／O能力的几个关键因素,对存储设备的吞吐量,PCI总线速率,SCSI通道的速率和网卡的传输速度等对服务器I／O性能的影响进行了较全面,深入的分析,最后提高一种利用服务器集群的方式提高VoD系统I／O能力的方法。     

An Operational Approach to the Semantics of Classes: Application to Type Checking

This paper presents a simple and natural semantics for object-oriented languages with classes and multiple inheritance. The model, called the Formal Class model, is an intermediate level between the algebraic specification of data type, and the implementation within an object-oriented language. Our model is equipped with an operational semantics based on conditional term rewriting. One important characteristic is the use of conditional selectors. It allows one to define a type with a flat or an ordered design. In this context, we define a safe and simple type system with single dispatch and simply covariant methods. This type system is extended to some practical aspects, such as abstract classes, abstract methods, protected methods, and super methods. We describe and compare flat and ordered designs and prove that the latter is finer than the former one. We also look at multicovariant methods and show ways to fix type-checking problems using single dispatch. We describe the least pessimistic solution. Lastly, we discuss the extension of our type checking to multiple dispatch and side effects. This paper synthesizes several practical results, their proofs, and algorithms.     

组件技术在B/S结构中的应用

研究了组件技术如何应用于基于B/S结构中的应用软件的开发。通过对W eb动态应用模式和分布式结构主要技术的分析,设计了基于组件的服务器的结构。最后阐述了组件技术应用于软件开发的意义。     

An experimental evaluation of I/O optimizations on differentapplications

Many large-scale applications have significant I/O requirements as well as computational and memory requirements. Unfortunately, the limited number of I/O nodes provided in a typical configuration of the modern message-passing distributed-memory architectures such as the Intel Paragon and the IBM SP-2 limits the I/O performance of these applications severely. In this paper, we examine some software optimization techniques and evaluate their effects in five different I/O-intensive codes from both small and large application domains. Our goals in this study are twofold. First, we want to understand the behavior of large-scale data-intensive applications and the impact of I/O subsystems on their performance and vice versa. Second, and more importantly, we strive to determine the solutions for improving the applications' performance by a mix of software techniques. Our results reveal that different applications can benefit from different optimizations. For example, we found that some applications benefit from file layout optimizations, whereas others take advantage of collective I/O. A combination of architectural and software solutions is normally needed to obtain good I/O performance. For example, we show that with a limited number of I/O resources, it is possible to obtain good performance by using appropriate software optimizations. We also show that beyond a certain level, imbalance in the architecture results in performance degradation even when using optimized software, thereby indicating the necessity of an increase in I/O resources     

一种SYN／Flooding攻击的对策

介绍了目前防范SYN/Flooding网络攻击的几种典型的方法,在模拟高速交换网络的环境下实施了SYN/Fooding网络攻击的实验,通过对网络带宽和系统遭受贡献的影响的分析和比较实验结果,指出现有系统的不足,并提出一种适用于高强度SYN/Flooding攻击的自适应cookies防范模型,在Linux系统中实现了该模型,实验结果表明该模型能捣鬼庐山强度的SYN/Flooding攻击,优于传统的防范策略。     

GENIUS I/O系统在小型连轧中的应用

介绍了GENIUS I/O系统在小型连轧的应用,并对其结构、通讯和组态方面进行了应用说明.     

一种在应用层通过信息隐藏实现的安全组播方案

根据多媒体组播应用程序的特点,结合数据隐藏的研究成果,提出了一种在应用层发放和管理密钥,并依靠密钥嵌入媒体流的方法来实现多媒体组播应用中的访问控制。     

IOMan:一种支持多操作系统远程启动和运行的I/O管理方法

为了降低用户使用和维护计算机系统的成本,基于透明计算模式提出了一种工作在局域网环境下的I/O管理方法:IOMan. IOMan只是用软件方法在客户端设置磁盘I/O重定向机制,按需动态下载数据,而不需要修改当前常用的操作系统如Windows的启动机制,也不影响其他I/O操作,能够支持多种操作系统的远程启动和应用程序的运行 . IOMan基于客户机/服务器模型,包括I/O Client和I/O Server两个部分,其中I/O Client工作在客户端,I/O Server工作在服务器端 . I/O Client通过重新定义访问磁盘的BIOS中断处理程序以及创建虚拟本地磁盘,将I/O请求发送给服务器;I/O Server响应客户端请求,读写服务器上存储的虚拟硬盘文件,然后以扇区形式将数据发送给I/O Client.     

Lemon: An MPI parallel I/O library for data encapsulation using LIME

We introduce Lemon, an MPI parallel I/O library that provides efficient parallel I/O of both binary and metadata on massively parallel architectures. Motivated by the demands of the Lattice Quantum Chromodynamics community, the data is stored in the SciDAC Lattice QCD Interchange Message Encapsulation format. This format allows for storing large blocks of binary data and corresponding metadata in the same file. Even if designed for LQCD needs, this format might be useful for any application with this type of data profile. The design, implementation and application of Lemon are described. We conclude with presenting the excellent scaling properties of Lemon on state-of-the-art high performance computers.Program summaryProgram title: LemonCatalogue identifier: AELP_v1_0Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AELP_v1_0.htmlProgram obtainable from: CPC Program Library, Queen?s University, Belfast, N. IrelandLicensing provisions: GNU General Public License version 3No. of lines in distributed program, including test data, etc.: 32 860No. of bytes in distributed program, including test data, etc.: 223 762Distribution format: tar.gzProgramming language: MPI and CComputer: Any which supports MPI I/OOperating system: AnyHas the code been vectorised or parallelised?: Yes. Includes MPI directives.RAM: Depending on input usedClassification: 11.5External routines: MPINature of problem: Distributed file I/O with metadataSolution method: MPI parallel I/O based implementation of LIME formatRunning time: Varies depending on file and architecture size, in the order of seconds     

An experimental evaluation of I/O optimizations on different applications

Many large scale applications have significant I/O requirements as well as computational and memory requirements. Unfortunately, the limited number of I/O nodes provided in a typical configuration of the modern message-passing distributed-memory architectures such as Intel Paragon and IBM SP-2 limits the I/O performance of these applications severely. We examine some software optimization techniques and evaluate their effects in five different I/O-intensive codes from both small and large application domains. Our goals in this study are twofold. First, we want to understand the behavior of large-scale data-intensive applications and the impact of I/O subsystems on their performance and vice versa. Second, and more importantly, we strive to determine the solutions for improving the applications' performance by a mix of software techniques. Our results reveal that different applications can benefit from different optimizations. For example, we found that some applications benefit from file layout optimizations whereas others take advantage of collective I/O. A combination of architectural and software solutions is normally needed to obtain good I/O performance. For example, we show that with a limited number of I/O resources, it is possible to obtain good performance by using appropriate software optimizations. We also show that beyond a certain level, imbalance in the architecture results in performance degradation even when using optimized software, thereby indicating the necessity of an increase in I/O resources.     

An efficient, low-cost I/O subsystem for network processors

An efficient I/O subsystem enables cost-effective network processing. To improve high-speed data transfer, the I/O subsystem sends data directly into the processing core's register file. An implementation of this subsystem in a single-chip network processor , the Pro/sup 3/, can sustain advanced inspection firewall processing of 2.5-Gbps TCP traffic.     

网络编程中各种I/0方式的比较与选择

本文以UNIX系统下ech0服务的编程实现为例,系统介绍各种I/O方式的特点.通过对比各种I/O方式的特点,探讨在实际应用中如何选取最优的I/O方式,并给出一个通用的I/O方式选择标准.     

New I/O technologies seek to end bottlenecks

New processors, hard drives, memory chips, networking standards and other technologies are pushing the limits of computer capabilities. However, the improved performance these developments promise for PCs, servers, and even embedded systems is being choked at a bottleneck caused by input/output (I/O) technology, which has failed to keep pace. To cope with this problem, vendor groups are releasing new I/O platforms. The new technologies promise faster performance, reduced latency, reduced CPU computational load, and more efficient and reliable systems. However, as is the case with many new technologies, there are concerns. For example, industry observers speculate that the new I/O technologies could become so popular that companies may use them inappropriately, thereby reducing their effectiveness. In addition, some users are worried that the different technologies are incompatible or that bridges between technologies could add programming complexity     

A New Approach to the Gas Dynamics Equation: An Application of the Decomposition Method

The Adomian decomposition method is used to implement the homogeneous gas dynamics equations. The analytic solution of the equation is calculated in the form of a series with easily computable components. The homogeneous problem is quickly solved by observing the self-canceling "noise" terms whose sum vanishes in the limit. Comparing the methodology with some other known techniques shows that the present approach is effective and powerful. Many test modeling problems from mathematical physics, both linear and nonlinear are discussed to illustrate the effectiveness and the performance of the decomposition method.     

用I/O完成端口设计多线程的服务应用程序

探讨了在Windows操作系统平台下用I/O完成端口开发多线程的服务器应用程序的方法。     

关于I/O模拟的讨论

详细分析Windows的I/O机制,提出了分别在用户级、系统级、驱动级的FO模拟操作,通过实际案例和源代码分享在I/O模拟上的得失,着重介绍鼠标与键盘的模拟.