A robust reconfiguration protocol for the dynamic update of component‐based software systems

This paper focuses on the dynamic reconfiguration of component‐based software systems. From a structural point of view, such systems are made of components linked together through their provided and required services, the code of components being defined by modules (e.g., jar files). Today, the ability to reconfigure component‐based systems at runtime faces limitations. Some component frameworks allow to dynamically reconfigure components – starting or stopping them, or changing how they are wired together for instance – but forbid any dynamic evolution of the modules defining their code. Other frameworks allow to dynamically update modules but at the cost of loosing control on component wires, preventing software architects or tools alike to decide how components are wired together. In this paper, we propose a component framework that addresses these limitations through a unified approach for the management of components and modules. Our approach uniquely enables to reconfigure both components and modules at runtime, without restrictions. We prototyped the proposed framework in Java and exercised various dynamic reconfigurations of component‐based systems. Furthermore, we formalized this framework and proved the correctness of its reconfiguration protocol with the Coq proof assistant. Copyright © 2017 John Wiley & Sons, Ltd.     

Linux TCP/IP协议栈的层次构件化

研究了Linux现有TCP／IP实现机制及与构件化密切相关的模块机制,实现了TCP／IF协议栈的层次构件化,搭建了一套更为灵活的TCP/IP协议栈的组织方式,证明了将构件技术引入Linux TCP／IP协议栈的可行性及优越性。     

ZLIP TCP/IP协议栈在嵌入式系统中的应用

ZLIP协议栈是一种极小的TCP／IP协议栈,该协议栈是免费的开源协议栈,可以适用于8位或16位的微处理器搭建的嵌入式系统。本文介绍了将ZLIP结合嵌入式平台,实现将嵌入式系统作为客户端接入网络中的应用,对ZLIP协议栈的特点和相关接口进行了分析。     

一种高速安全反向代理服务器的设计与实现

安全反向代理服务器架设在真实网页服务器与用户浏览器之间靠近真实服务器的一侧,通过传输层安全协议保障用户与真实服务器之间的通信.作为基于传输层安全协议的虚拟专用网服务器的一个最重要的组成部分,安全反向代理有着极大的商业价值和技术含量.在FreeBSD-6.3的基础上设计并实现了一个与传统TCP/IP并行的TCP/IP跳转表.基于TCP/IP跳转表设计并实现了一种多加速卡调度算法.设计并实现了直接从加速卡队列获取数据包的代理转发协议栈.设计并实现了基于后台真实服务器反馈的负载均衡算法.测试表明,由这些算法和协议栈组成的高速安全反向代理服务器新进连接数达到了国内领先水平.     

嵌入式协议栈可重构性分析与设计实现

本文通过对协议栈的可重构性进行分析,设计并实现了一种可重构的嵌入式TCP／IP协议栈,并介绍了关键技术的实现细节。该协议栈可以根据用户需求重构为IPv4、IPv6、双栈协议栈等多种协议栈,具有良好的灵活性、可移植性。该协议栈已成功应用在嵌入式双向通信平台上,通过实际网络测试表现出良好的性能和可靠性。在主频为66MHz的ARM7CPU上运行,吞吐率可达1．5MB／s以上,目标代码大小仅为传统协议栈的30％左右,并可满足IPv4到IPv6网络过渡时期嵌入式设备的网络需求。     

Weaves: A Framework for Reconfigurable Programming

This paper presents a language independent runtime framework—called Weaves—for object based composition of unmodified code modules that enables selective sharing of state between multiple control flows through a process. Furthermore, the framework allows dynamic instantiation of code modules and control flows through them. In effect, weaves create intra-process modules (similar to objects in OOP) from code written in any language. Applications can be built by instantiating Weaves to form Tapestries of dynamically interacting code. The framework enables objects to be arbitrarily shared—it is a true superset of both processes as well as threads, with code sharing and fast context switching time similar to threads. Weaves does not require any special support from either the language or application code—practically any code can be weaved. Weaves also include support runtime loading and linking of object modules enabling the next generation of highly dynamic applications. This paper presents the elements of the Weaves framework and its implementation on the Linux platform over source-code independent ELF object files. The current implementation has been validated over Sweep3D, a benchmark for 3D discrete ordinates neutron transport (Koch et al. Trans. Am. Nucl. Soc. 65 (198) [1992]), and a user-level port of the Linux 2.4 family kernel TCP/IP protocol stack.     

区域网络TCP/IP协议栈的性能分析

针对ＴＣＰ／ＩＰ在功能和性能两个方面所表现出的内在缺陷,在对传统协议功能研究的基础上,分析了ＴＣＰ／ＩＰ协议栈在区域网络环境的动态行为,特别是应用报文,ＴＣＰ窗口和分组大小,某些ＴＣＰ改进算法对单向和双向的批量和事务应用的性能影响,并从协议机制的角度揭示和探讨造成性能差异的原因。     

Modbus/TCP协议在带式输送机视频传感系统中的应用

给出了带式输送机视频传感系统的硬件结构,阐述了Modbus/TCP协议在该系统中的应用方法,包括网络程序开发包协议栈及Modbus/TCP协议的实现。测试结果表明,该系统能够实时、准确地传输并显示带式输送机的开停、堆煤、着火、跑偏、撕裂、煤量、速度信息。     

采用Java技术开发可复用的Web表示层构件

JSP和Servlet技术为Web应用系统的构建提供了强大的支持.但是,许多开发者常常会忽略掉一些关键的设计原则,开发出难以维护、难以测试的系统.基于分层次的结构,以Java技术为基础,开发控制器构件、值传递构件、用户会话管理构件、格式构件和JSP页面测试驱动构件,最后组装成Web表示层构件.该构件化的开发方法,提高了系统的可复用度,并且可以在较短的时间内组装出符合用户需求的新系统,从而降低了系统的开发成本及升级维护费用,并能增强系统的可测试性和可维护性.为基于Web的应用系统开发提供了新的思路和方法.     

防火墙工作原理与技术之研究

防火强的工作原理简单的说就是对通信包的接受或者拒绝。大多数防火墙采用的技术和标准均有所不同。这些防火墙的形式多种多样：有的取代系统上已经装备的TCP／IP协议栈,有的在已有的协议栈上建立自己的软件模块,还有一些应用型的防火墙只对特定类型的网络连接提供保护（比如SMTP或者HTTP协议等）,以上的产品都可以叫做防火墙,因为他们的工作原理都是一样的：分析出入防火墙的数据包,决定接受还是丢弃。     

uIP TCP/IP协议栈在51系列单片机上的应用

uIP协议栈是一种免费的可实现的极小的TCP／IP协议栈，可以使用于由8位或16位微处理器构建的嵌入式系统。本文分析了uIP协议栈的结构和应用接口．并讨论了如何将其应用到51系列单片机上。     

一种使用TCP/IP协议实现无线传感器网络互连的新型设计

传统的TCP/IP协议栈由于规模庞大而不能用于资源有限的无线传感器网络,在分析无线传感器网络环境的基础上,研究针对无线传感器节点的TCP/IP协议栈的设计,引入协议的头标压缩技术,提出一种采用两种节点、两种栈设计的新型模型.模型中除普通节点外附加了少量的超级节点,普通节点采用压缩TCP/IP协议,超级节点实现压缩和标准TCP/IP协议之间的转换,并保证每一个节点与外部Internet高效无缝的连接.     

一种新的嵌入式TCP/IP协议栈的研究与实现

将以家电为代表的嵌入式系统连接到网络中，关键是TCP／IP协议栈的实现。为了适应嵌入式系统的软件、硬件环境并满足实际要求，对标准TCP／IP协议的部分模块进行了裁判，设计了一种适合8位／16位微控制系统的嵌入式TCP／IP协议栈。新的协议栈实现了标准TCP／IP协议栈的主要功能，对系统资源要求少，为家电网络化管理创造了条件。     

一种虚拟路由器的体系结构及实现

提出了一种虚拟路由器体系结构，并对其中的关键组成部件如虚拟协议栈模块、虚拟路由协议模块以及虚拟管理模块等功能和实现进行了描述，为了实现单一代码能够运行多个实例，使用封装技术修改了协议栈代码、路由协议代码和路由器中其它的功能模块代码，并以BSD4.3为基础实现了虚拟路由器原型。通过对原型的测试，表明提出的体系结构和实现方法能够达到预期效果，具有实际应用价值。     

一种提高TCP/IP网络协议传输速率的方法

随着网络技术的快速发展,主机间的通信速率已提高到千兆数量级,同时多媒体应用还要求网络协议支持实时业务。因此对传统的TCP／IP协议栈进行研究,找出影响它的传输速率的因素,并提出相应的改进方法具有重要的意义。针对原协议的数据输出过程中从数据缓冲区到网络内核缓冲区有一次数据拷贝的过程,采用共享缓存区的方法避免了这次拷贝,该方法提高了网络协议传输速率的有效性,缩短了网络的输出时间。     

面向模型的动态架构

为了使应用系统能够动态调整以适应用户需求的变化,提出一种面向模型的动态应用架构。该架构以生成的框架对象实例来调度各应用构件的工作,在框架层解释模型与构件间的引用和交互过程。通过把用户业务需求这一抽象概念具体化为可直接操控的模型,给出一种面向模型的动态架构演化技术。设计并实现了一个支撑平台IPmis,为具有动态调整能力的应用系统的开发和运行提供了可视化的集成环境。在此平台上完成了医疗保险集成系统的开发,满足了随用户需求变更和动态调整的需要。     

Architecting and implementing distributed Web applications using the graph‐oriented approach

This paper presents a graph‐oriented framework, called WebGOP, for architecture modeling and programming of Web‐based distributed applications. WebGOP is based on the graph‐oriented programming (GOP) model, under which the components of a distributed program are configured as a logical graph and implemented using a set of operations defined over the graph. WebGOP reshapes GOP with a reflective object‐oriented design, which provides powerful architectural support in the World Wide Web environment. In WebGOP, the architecture graph is reified as an explicit object which itself is distributed over the network, providing a graph‐oriented context for the execution of distributed applications. The programmer can specialize the type of graph to represent a particular architecture style tailored for an application. WebGOP also has built‐in support for flexible and dynamic architectures, including both planned and unplanned dynamic reconfiguration of distributed applications. We describe the WebGOP framework, a prototypical implementation of the framework on top of SOAP, and a performance evaluation of the prototype. The prototype demonstrated the feasibility of our approach. Results of the performance evaluation showed that the overhead introduced by WebGOP over SOAP is reasonable and acceptable. Copyright © 2003 John Wiley & Sons, Ltd.     

Toward the adaptation of component‐based architectures by model transformation: behind smart user interfaces

Graphical user interfaces are not always developed for remaining static. There are GUIs with the need of implementing some variability mechanisms. Component‐based GUIs are an ideal target for incorporating this kind of operations, because they can adapt their functionality at run‐time when their structure is updated by adding or removing components or by modifying the relationships between them. Mashup user interfaces are a good example of this type of GUI, and they allow to combine services through the assembly of graphical components. We intend to adapt component‐based user interfaces for obtaining smart user interfaces. With this goal, our proposal attempts to adapt abstract component‐based architectures by using model transformation. Our aim is to generate at run‐time a dynamic model transformation, because the rules describing their behavior are not pre‐set but are selected from a repository depending on the context. The proposal describes an adaptation schema based on model transformation providing a solution to this dynamic transformation. Context information is processed to select at run‐time a rule subset from a repository. Selected rules are used to generate, through a higher‐order transformation, the dynamic model transformation. This approach has been tested through a case study which applies different repositories to the same architecture and context. Moreover, a web tool has been developed for validation and demonstration of its applicability. The novelty of our proposal arises from the adaptation schema that creates a non pre‐set transformation, which enables the dynamic adaptation of component‐based architectures. Copyright © 2014 Copyright © 2014 John Wiley & Sons, Ltd.     

基于构件动态演化的行为一致性验证方法

为了保证构件在动态演化中的行为一致性,避免不合法的构件演化,提出一种基于进程代数的构件模型,引入对外主动请求接口和内部连接,形式化描述构件及其对外交互协议,给出相关定理和验证算法。实例证明,该构件模型可以验证动态演化中的接口兼容性、外部交互行为一致性,以及运行时行为完整性。     

一种基于TPM芯片的计算机安全体系结构

针对现行通用个人计算机基于开放架构、存在诸多攻击点等安全问题,提出了一种基于TPM安全芯片的新型计算机体系结构。设计并实现了基于安全芯片的软件协议栈TSS,在安全芯片中使用软件协议栈,通过核心服务API来调用核心服务模块,解决远程通信的平台信任问题。设计并实现了基于多协议的授权和认证管理,实现上层应用和TPM之间的授权会话及授权认证,从而保证计算机能够完成安全计算和安全存储的工作,使计算平台达到更高的安全性。