面向方面的中间件

中间件应用领域的不断拓展,给中间件体系结构的设计带来了困难,中间件的体系结构必须在通用性与专用性之间寻找平衡。传统的中间件体系结构产生这些问题的一个基本原因是:使用垂直分解过程获得的软件分解模型不能同时模块化共存的正交设计需求。论述了针对专门领域的面向方面中间件开发的三种工具:AspectIX和QuO处理QoS关注点,DIL从功能代码中分离协议实现。在建造一个中间件系统时,使用这些工具可以获得较好的模块性、可配置性和代码的演化性。     

容错CORBA系统的设计与实现

CORBA是基于对象技术的中间件平台的最流行的标准之一 .CORBA对应用屏蔽了分布式系统的异构性 .然而目前 CORBA还没有考虑容错问题 ,而容错是运行在异构环境中的分布式应用的核心问题之一 .因此 ,在最近几年许多为 CORBA应用添加可靠性和可用性的建议出现在各种文献上 .本文分析了这些建议的优、缺点 ,并提出了一个新颖的与 CORBA兼容的方法 ,这种方法不同于异步环境中可靠结构的分发方法 .     

Architectures to Survive Technological and Business Turbulences

Survivable architectures are needed so that the current and future systems can tolerate the usual turbulences of technology and business climate. This paper, based on insights gained through practical experience with several architectural projects in the telecom industry and active participation in the standards bodies, highlights the work being done on survivable architectures. Instead of presenting theoretical models, this paper relies on best practices and explains the concepts through a detailed case study. In particular, the concepts of separating the technology independent models from the technology specific models and externalizing the business process flows from the system components are shown to be of practical value.     

流程控制系统中数据访问中间件设计与实现

在自动化应用中,传统的直接访问数据库方法和Web数据访问方法,在实时性、安全性、安装维护等方面存在不足。针对此种不足设计开发了数据访问中间件。作为一个独立的软件产品,它适合应用于工业自动化中B/S模式的分布式在线监控系统中。中间件采用多线程程序设计、两子层通信协议、ADO数据访问接口、切断式记录集等技术,以VC++语言开发实现,提高了系统的实时性、安全性和可维护性。本中间件成功应用某电厂热经济型在线分析系统中,取得了良好的应用成效。     

适用于分布式系统的多级安全访问控制策略

针对分布式信息系统的资源共享及安全互操作问题,在多级安全模型基础上加入管理平台和中间件模块,提出一种适用于分布式系统的多级安全访问控制策略,保证数据机密性和访问过程安全可控。用XACML语言对安全策略进行标准化描述,并对策略进行安全性和灵活性分析。     

ARMADA Middleware and Communication Services

Real-time embedded systems have evolved during the past several decades from small custom-designed digital hardware to large distributed processing systems. As these systems become more complex, their interoperability, evolvability and cost-effectiveness requirements motivate the use of commercial-off-the-shelf components. This raises the challenge of constructing dependable and predictable real-time services for application developers on top of the inexpensive hardware and software components which has minimal support for timeliness and dependability guarantees. We are addressing this challenge in the ARMADA project.ARMADA is set of communication and middleware services that provide support for fault-tolerance and end-to-end guarantees for embedded real-time distributed applications. Since real-time performance of such applications depends heavily on the communication subsystem, the first thrust of the project is to develop a predictable communication service and architecture to ensure QoS-sensitive message delivery. Fault-tolerance is of paramount importance to embedded safety-critical systems. In its second thrust, ARMADA aims to offload the complexity of developing fault-tolerant applications from the application programmer by focusing on a collection of modular, composable middleware for fault-tolerant group communication and replication under timing constraints. Finally, we develop tools for testing and validating the behavior of our services. We give an overview of the ARMADA project, describing the architecture and presenting its implementation status.     

基于ICE的局域网监控设计与实现

介绍了利用ICE(internet communication engine)中间件开发应用程序方法和优势,提出了一种基于ICE的局域网监控系统方案.阐述了整个方案的实现功能和关键技术.该方案采用ICE中间件技术实现了一种分布式的通信代理模块,使得各个模块之间可以透明的通信,提高了系统的安全性、健壮性、可扩展性和可维护性.     

DCAM平台下的分布式方面构件模型及协同框架的研究*

由于方面化中间件平台DCAM的方面内核实现机制没有提供对分布式环境下方面构件通信的支持,扩展了DCAM中方面内核的方面调用机制,提出了分布式方面构件模型以及分布式环境下方面构件的协同框架。扩展后的DCAM平台不仅保持了原平台对POJO的支持,同时通过对分布式协同框架的引入,使平台在分布式环境下具有更好的可扩展性和容错性,满足了按需计算的需求。最后通过应用实例对DCAM的分布式模型进行了可行性验证并给出了性能分析。     

基于P／S模式的分布对象中间件异步通信接口

对分布对象中间件异步通信中的时间、空间和流程的解耦问题进行研究,分析当前分布对象中间件异步通信机制存在的问题。基于CORBA分布环境引入P／S发布订阅系统,构建基于P／S模式的CORBA通信体系。阐述该通信体系的体系结构及其接口的封装与设计,对支持这种通信体系的使能技术进行说明。     

浅析中间件技术的研究现状

中间件是为解决分布式环境中的异构问题而提出的,它是当前软件技术发展的一个潮流,是发展最快的软件品种之一。该文阐述了中间件技术的概念、分类、优势以及作用,同时提出了目前中间件的发展趋势。     

基于J2EE中间件技术的分布式系统建模

对当前流行的几种中间件技术进行了分析,并对基于构件的中间件技术J2EE与其它中间件进行了比较研究.在基于理论的研究基础之上,提出了系统的体系结构建模方案.     

Using Logical Rings to Solve the Distributed Mutual Exclusion Problem with Fault Tolerance Issues

In this paper, we investigate distributed mutual exclusion algorithms and delineate the features of a new distributed mutual exclusion algorithm. The basis of the algorithm is the logical ring structure employed in token-based mutual exclusion algorithms. Specifically, there exists dynamic properties of the logical ring that, given certain restrictions regarding message traffic flow, passively give useful information about the location of the token. Effectively, the algorithm demonstrates a type of intelligent routing that identifies useful shortcuts in the routing of the token. The result is a reduction in the total number of messages exchanged prior to the execution of the critical section as compared to the algorithm proposed by Fu and Tzeng [3]. Furthermore, the algorithm allows for an increased degree of fairness in a lightly loaded system than that allowed by Fu and Tzeng's algorithm. The paper also addresses failure recovery issues.     

A Crash Course in λ-Calculus

Thetalkpresentedthebasicresultsofλ-calculus.Aftergivingthesyntaxofterms(concretesyntax,abstractsyntaxusingdeBruijn'sindices)andthedefinitionofsubstitution,theβ-reductionrelation(strongreduction)ispresentedanditsmainpropertieslisted:.parallel-moveslemma,leadingtoconfluenceandtheChurch-Rosserpropertyofβ-conversion,anduniquenessofnormalforms.standardisationandthecompletenessofthenormalreductionstrategy(leftmost-outermost).finally,η-conversionisdiscussed,andtheseparabilityproperty(Bohmtheorem…     

Integrated Adaptive QoS Management in Middleware: A Case Study

Distributed real-time and embedded (DRE) systems in which application requirements and environmental conditions may not be known a priori—or which may vary at run-time—can benefit from an adaptive approach to management of quality-of-service (QoS) to meet key constraints, such as end-to-end timeliness. Moreover, coordinated management of multiple QoS capabilities across multiple layers of applications and their supporting middleware can help to achieve necessary assurances of meeting these constraints.This paper offers two contributions to the study of adaptive DRE computing systems: (1) a case study of our integration of multiple middleware QoS management technologies to manage quality and timeliness of imagery adaptively within a representative DRE avionics system and (2) empirical results and analysis of the impact of that integration on key trade-offs between timeliness and image quality in that system.This work was supported in part by AFRL contract F33615-97-D-1155/0005 (WSOA), NSF ITR CCR-0312859, Siemens, and DARPA/AFRL contracts F33615-03-C-4112, F30602-98-C-0187 and F33615-00-C-1694. Approved for public release, distribution unlimited.Christopher D. Gill is an Assistant Professor in the Department of Computer Science and Engineering at Washington University in St. Louis. He has published over 50 refereed technical articles in leading journals, conferences, workshops, and book series. His research focuses on distributed real-time embedded systems, with particular emphasis on adaptive mresource management, scheduling, and software design and implementation for time-and-space constrained systems. Dr. Gill has chaired numerous workshop and conference program committees, and has participated widely in review panels and standards organizations in the distributed and real-time systems areas. The research he has led has produced several freely available open-source software frameworks including the Kokyu scheduling and dispatching framework and the nORB small-footprint real-time object request broker.Jeanna Gossett joined The Boeing Company in 1999 as a member of Bold Stroke/Open Systems Architecture team. Jeanna has worked on several CRAD projects including Weapon Systems Open Architecture (WSOA) where she was responsible for incorporating quality of service and resource management software technology into the fighter aircraft real-time embedded system application. Jeanna has since joined the F/A-18 New Product Development Mission Systems team. Prior to joining The Boeing Company in 1999, she worked in the telecommunications industry as an embedded systems developer at Ericsson and Siemens AG. Jeanna received a B.S. in Electrical Engineering from Southern Illinois University, Edwardsville and is a 2005 M.B.A. candidate at Washington University in St. Louis.David Corman is a Technical Fellow at the Boeing Company, located in St. Louis, Mo. Dave is the chief scientist for the Network Centric Operations (NCO) thrust in Phantom Works (PW) and is responsible for developing the NCO technology research agenda and investment strategy. He is also the Principle Investigator (PI) for a variety of Air Force and Defense Advanced Research Project Agency (DARPA) programs that are producing technologies for integrating legacy platforms into the emerging Global Information Grid and for autonomous control of unmanned systems. Since joining the former McDonnell-Douglas (now part of the Boeing Company) in 1983, Dave has worked on numerous projects ranging from embedded systems to large C4I and weapon systems. A major focus of Daves career has been on the development of C4I system simulations and in mission planning system development for aircraft and missiles. He has also served as a consultant to many weapon system and C4I programs in St. Louis, Seattle, and California. Prior to joining McDonnell-Douglas, Dave spent five years at the Johns Hopkins University Applied Physics Laboratory. He was the first recipient of a Naval Research Laboratory Fellowship from the University of Maryland—College Park where he received his PhD in Electrical Engineering in 1983.Joseph Loyall is a division scientist at BBN Technologies, where he leads the Distributed Real-time Embedded (DRE) systems research thrust in the Distributed Systems Advanced Middleware Technology group. He is actively involved in developing integrated dynamic resource management capabilities and advanced software engineering using model driven architecture (MDA) approaches, and in applying adaptive behavior to operational embedded systems such as collections of unmanned and manned air vehicles. Dr. Loyall has a Ph.D. and M.S. in computer science from the University of Illinois and a B.S. in computer science from Indiana University. He can be contacted at jloyall@bbn.com.Richard E. Schantz is a principal scientist at BBN Technologies in Cambridge, Mass., where he has been a key contributor to advanced distributed computing R&D for the past 30 years. His research has been instrumental in defining and evolving the concepts underlying middleware since its emergence in the early days of the Internet. He was directly responsible for developing the first operational distributed object computing capability and transitioning it to production use. More recently, he has led research efforts toward developing and demonstrating the effectiveness of middleware support for adaptively managed Quality Of Service control, as principal investigator on a number of key DARPA projects in the areas of adaptive real-time behavior, survivability and advanced software engineering. Schantz received his Ph.D. degree in Computer Science from the State University of New York at Stony Brook, in 1974.Michael Atighetchi is a senior scientist at BBN Technologies and a senior member of the Distributed Systems Advanced Middleware Technology group. His interests include use of adaptation in survivable systems, network and operating system security, and distributed coordination. Contact him at matighet@bbn. comDouglas C. Schmidt (d.schmidt@vanderbilt.edu) is a Professor of Electrical Engineering and Computer Science, Associate Chair of the Computer Science and Engineering program, and a Senior Researcher in the Institute for Software Integrated Systems (ISIS) at Vanderbilt University. He has published over 300 technical papers and books that cover a range of research topics, including patterns, optimization techniques, and empirical analyses of software frameworks and domain-specific modeling environments that facilitate the development of distributed real-time and embedded (DRE) middleware and applications running over high-speed networks and embedded system interconnects. Dr. Schmidt has served as a Deputy Office Director and a Program Manager at DARPA, where he led the national R&D effort on middleware for DRE systems.     

基于消息队列机制的中间件及其在一卡通项目中的应用

中间件为网络环境下的应用程序提供了通信的普遍方法和相对于网络与操作系统的独立性,消息队列机制是信息交换的一种技术,基于消息队列机制的中间件产品应用于上海市公交一卡通项目中,实现了广域网中跨系统平台、在数据量的通信。