A Component-Based Software Configuration Management Model and Its Supporting System

Software configuration management(SCM)is an important key technology in software development.Component-based software development (CBSD)is an emerging paradigm in software development.However,to apply CBSD effectively in real world practice,supporting SCM in CBSD needs to be further investigated.In this paper,the objects that need to be managed in CBSD is analyzed and a component-based SCM model is presented.In this model,Components,as the integral logical constituents in a system,are managed as the basic configuration items in SCM,and the relationships between/among components are defined and maintained.Based on this model.a configuration management system is implemented.     

QoS-Aware Automatic Service Composition: A Graph View

In the research of service composition,it demands efficient algorithms that not only retrieve correct service compositions automatically from thousands of services but also satisfy the quality requirements of different service users.However,most approaches treat these two aspects as two separate problems,automatic service composition and service selection.Although the latest researches realize the restriction of this separate view and some specific methods are proposed,they still suffer from serious limitations in scalability and accuracy when addressing both requirements simultaneously.In order to cope with these limitations and efficiently solve the combined problem which is known as QoS-aware or QoS-driven automatic service composition problem,we propose a new graph search problem,single-source optimal directed acyclic graphs (DAGs),for the first time.This novel single-source optimal DAGs (SSOD) problem is similar to,but more general than the classical single-source shortest paths (SSSP) problem.In this paper,a new graph model of SSOD problem is proposed and a Sim-Dijkstra algorithm is presented to address the SSOD problem with the time complexity of O(n log n + m) (n and m are the number of nodes and edges in the graph respectively),and the proofs of its soundness.It is also directly applied to solve the QoS-aware automatic service composition problem,and a service composition tool named QSynth is implemented.Evaluations show that Sim-Dijkstra algorithm achieves superior scalability and efficiency with respect to a large variety of composition scenarios,even more efficient than our worklist algorithm that won the performance championship of Web Services Challenge 2009.     

An objective-oriented approach to program comprehension using multiple information sources

Program comprehension is a key activity throughout software maintenance and reuse. The knowledge acquired through comprehending programs can guide engineers to perform various kinds of software maintenance and reuse tasks. The effective comprehension strategy and the associated efficient approach, as well as the sophisticated tool support, are the indispensable elements for an entire solution to program comprehension to reduce the high costs of this nontrivial activity. This paper presents an objective-oriented comprehension strategy, contrasting to the traditional comprehensive understanding strategy in the literature. It is a kind of on-demand understanding for specific tasks and more effective in practice. In addition, using multiple information sources to understand programs is proposed with the corresponding framework. From these two points of views, we propose a feature-oriented program comprehension approach using requirement documentation. This approach aims at a specific category of feature-related software maintenance and reuse tasks. Case studies are conducted to evaluate the proposed solution. Results from the studied cases show that the experimental prototype provides more explicit advices for software engineers when performing these tasks.     

Reconfigurable Optical Bus and Performance Optimization

With the advent of optical fiber and other advanced technologies in solid state,pipelining signals at the wire(or transmission line)level has becomr possible.This has,in turn,made the slotted bus a potential candidate for interconnection networks(IN)for tightly coupled multiprocessor systems.However,a bus an provide only limited bandwidth.Though slotted bus can provide considerably more bandwith in comparison to the traditional non-slotted bus,it is not enough for fine-grain parallel applications run on the shared-memory systems.One well known method to increase the effective bandwidth of a slotted bus in the LAN/MAN environment is to reuse the bandwwidth by reusing slots.However,in a tightly coupled environment reusing slots is not a lucrative option because the significant buffering needs arising from slot reuse will introduce intolerable delay.In this paper we propose a methodology to reuse part of the bandwith available from temporal and spectral bandwidth expansion with none of minimum buffering delay,resulting in significant performance improvement in both the effective throughput and response time(communication latency).The proposed method entails the design and analysis of a re-configurable bus structure with both temporal and spectral bandwidth expansion and a polynomial time algorithm for optimal configurations for given traffic conditionslWe have compared the performance of our reconfigured bus with that of the traditional slotted bus for uniform and localized traffic pattern and founr that the reconfigured bus outperforms the traditional slotted bus substantially in many practical scenarios.     

Effect of Look-Ahead Depth in Evolutionary Checkers

It is intuitive that allowing a deeper search into a game tree will result in a superior player to one that is restricted in the depth of the search that it is allowed to make. Of course, searching deeper into the tree comes at increased computational cost and this is one of the trade-offs that has to be considered in developing a tree-based search algorithm. There has been some discussion as to whether the evaluation function, or the depth of the search, is the main contributory factor in the performance of an evolved checkers player. Some previous research has investigated this question (on Chess and Othello), with differing conclusions. This suggests that different games have different emphases, with respect to these two factors. This paper provides the evidence for evolutionary checkers, and shows that the look-ahead depth (like Chess, perhaps unsurprisingly) is important. This is the first time that such an intensive study has been carried out for evolutionary checkers and given the evidence provided for Chess and Othello this is an important study that provides the evidence for another game. We arrived at our conclusion by evolving various checkers players at different ply depths and by playing them against one another, again at different ply depths. This was combined with the two-move ballot (enabling more games against the evolved players to take place) which provides strong evidence that depth of the look-ahead is important for evolved checkers players.     

A Personalized Information Dissemination System Based on How—Net

The information dissemination model is becoming increasingly important in wide-area information systems,In this model,a user subscribes to an information dissemination service by submitting profiles that describe his interests.There have been several simple kinds of information dissemination services on the Internet such as mailing list,but the problem is that it provides a crude granularity of interest matching.A user whose information need does not exactly match certain lists will either receive too many irrelevant or too few relevant messages.This paper presents a personalized information dissemination model based on HowNet,which uses a Concept Network-Views(CN-V) model to support information filtering,user‘s interests modeling and information recommendation.A Concept Network is constructed upon the user‘s profiles and the content of documents,which describes concepts and their relations in the content and assigns different weights to these concepts.Usually the Concept Network is not well arranged,from which it is hard to find some useful realtions.so several views from are extracted it to represent the important relations explicitly.     

Designing efficient proxy signature schemes for mobile communication

Proxy signature is an active cryptographic research area, and a wide range of literatures can be found nowadays suggesting improvement and generalization of existing protocols in various directions. However, from the efficiency view, many proposed proxy signature schemes in these literatures are not satisfying and cannot fit to the mobile communication. Therefore, there is a desire to design efficient proxy signature schemes. Based on Boneh et al＇s pairing-based short signature, this paper presents two proxy signature schemes. One is proxy-protected signature scheme, and the other is proxy aggregate signature scheme. Since both of them can achieve high efficiency, it is believed that they are specially suitable for mobile communication environment.     

Formal Reasoning About Finite-State Discrete-Time Markov Chains in HOL

Markov chains are extensively used in modeling different aspects of engineering and scientific systems, such as performance of algorithms and reliability of systems. Different techniques have been developed for analyzing Markovian models, for example, Markov Chain Monte Carlo based simulation, Markov Analyzer, and more recently probabilistic model-checking. However, these techniques either do not guarantee accurate analysis or are not scalable. Higher-order-logic theorem proving is a formal method that has the ability to overcome the above mentioned limitations. However, it is not mature enough to handle all sorts of Markovian models. In this paper, we propose a formalization of Discrete-Time Markov Chain (DTMC) that facilitates formal reasoning about time-homogeneous finite-state discrete-time Markov chain. In particular, we provide a formal verification on some of its important properties, such as joint probabilities, Chapman-Kolmogorov equation, reversibility property, using higher-order logic. To demonstrate the usefulness of our work, we analyze two applications: a simplified binary communication channel and the Automatic Mail Quality Measurement protocol.     

Web Service Choreography: Unanimous Handling of Control and Data

To provide an effective service-oriented solution for a given business problem, it is necessary to explore all available options for providing the required functionality while ensuring a flawless data transfer within the composed services. Existing service composition approaches fall short of this ideal, as functional requirements and data mediation are not considered in a unified framework. We propose a service composition framework that addresses both of these aspects by integrating existing techniques in formal methods, service oriented computing and data mediation. Our framework guarantees the correct interaction of services in a composition by verifying certain behavioral constraints, and resolving data mismatches at semantic, syntactic and structural levels, in a unified manner. A tableau based algorithm is used to generate and explore compositions in a goal-directed fashion that proves or disproves the existence of a service choreographer. Data models, to detect and resolve data mismatches, are generated using WSDL documents and regular expressions. We also apply our framework to examples adapted from the existing service composition literature that provide strong testimony that the approach can be effectively applied in practical settings.     

ABC:基于体系结构、面向构件的软件开发方法

基于构件的软件复用和开发被认为是提高软件开发效率和质量的有效途径,并在分布式系统中得到了广泛的应用.但是,目前的软件构件技术主要还是着眼于构件实现模型和运行时互操作,缺乏一套系统的方法以指导整个开发过程.近年来,以构件为基本单元的软件体系结构研究取得了较大的发展.它通过对软件系统整体结构和特性的描述,为面向构件的软件开发提供了一个自顶向下的途径.介绍了一种以软件体系结构为指导,面向构件的软件开发方法,试图为基于构件的软件复用提供一种有效的解决方案.这种方法主要是将软件体系结构引入到软件开发的各个阶段,作为系统开发的蓝图,利用工具支持的自动转换机制缩小从高层设计到实现的距离,而后在构件平台的运行支持下实现自动的系统组装生成.     

基于软件体系结构的构件组装工具ABC-Tool

软件朝着越来越复杂和庞大的趋势发展,因此对更有效的软件开发技术的需求十分迫切,近年来,软件体系结构、构件技术和软件复用技术等开始在软件开发中发挥重要作用,成为软件工程领域研究的热点,在基于构件复用的开发方法中,构件组装技术是关键,而且一直以来也是难点所在,ABC(architecture-based component composition)是一种基于软件体系结构、面向构件的软件开发方法,介绍了为ABC方法提供有效支持的工具ABC-Tool,ABC-Tool以软件体系结构为设计蓝图,以构件为基本开发单元,在不修改构件源代码的前提下,通过可视化的图形建模方式,从体系结构的高层设计逐层映射到底层实现,将可运行或可部署的构件组装为最终的可正确运行的系统。     

软件体系结构驱动的运行环境

由于软件体系结构以隐性的方式存在，结构的问题被传播到平台内，运行时软件体系结构不能在应用层次上被观察和控制，系统难以联机动态演化．在现有的中间件平台之上设计了一个面向应用、开放的、软件体系结构驱动的分布式远行环境SADRE（Software Architecture—Driven Runtime Environment），软件体系结构在可运行系统中以一类实体显性地表示,体系结构描述作为核心元素被整个分布式运行环境共事，成为系统调度、通信的依据．从而驱动用户应用的运行．SADRE为灵活的动态体系结构提供了良好的支持，提高了系统的柔性和扩展性．     

An Approach for Recovering Distributed System Architectures

Reasoning about software systems at the architectural level is key to effective software development, management, evolution and reuse. All too often, though, the lack of appropriate documentation leads to a situation where architectural design information has to be recovered directly from implemented software artifacts. This is a very demanding process, particularly when involving recovery of runtime abstractions (clients, servers, interaction protocols, etc.) that are typical to the design of distributed software systems. This paper presents an exploratory reverse engineering approach, called X-ray, to aid programmers in recovering architectural runtime information from a distributed system's existing software artifacts. X-ray comprises three domain-based static analysis techniques, namely component module classification, syntactic pattern matching, and structural reachability analysis. These complementary techniques can facilitate the task of identifying a distributed system's implemented executable components and their potential runtime interconnections. The component module classification technique automatically distinguishes source code modules according to the executables components they implement. The syntactic pattern matching technique in turn helps to recognise specific code fragments that may implement typical component interaction features. Finally, the structural reachability analysis technique aids in the association of those features to the code specific for each executable component. The paper describes and illustrates the main concepts underlying each technique, reports on their implementation as a suit of new and off-the-shelf tools, and, to give evidence of the utility of the approach, provides a detailed account of a successful application of the three techniques to help recover a static approximation of the runtime architecture for Field, a publicly-available distributed programming environment.     

An architectural approach to the correct and automatic assembly of evolving component-based systems

Software components are specified, designed and implemented with the intention to be reused, and they are assembled in various contexts in order to produce a multitude of software systems. However, in the practice of software development, this ideal scenario is often unrealistic. This is mainly due to the lack of an automatic and efficient support to predict properties of the assembly code by only assuming a limited knowledge of the properties of single components. Moreover, to make effective the component-based vision, the assembly code should evolve when things change, i.e., the properties guaranteed by the assembly, before a change occurs, must hold also after the change. Glue code synthesis approaches technically permit one to construct an assembly of components that guarantees specific properties but, practically, they may suffer from the state-space explosion phenomenon.In this paper, we propose a Software Architecture (SA) based approach in which the usage of the system SA and of SA verification techniques allows the system assembler to design architectural components whose interaction is verified with respect to the specified properties. By exploiting this validation, the system assembler can perform code synthesis by only focusing on each single architectural component, hence refining it as an assembly of actual components which respect the architectural component observable behaviour. In this way code synthesis is performed locally on each architectural component, instead of globally on the whole system interactions, hence reducing the state-space explosion phenomenon.The approach can be equally well applied to efficiently manage the whole reconfiguration of the system when one or more components need to be updated, still maintaining the required properties. The specified and verified system SA is used as starting point for the derivation of glue adaptors that are required to apply changes in the composed system. The approach is firstly illustrated over an explanatory example and is then applied and validated over a real-world industrial case study.     

基于工作流引擎的构件组装体系结构

近年来,软件体系结构(SA)、基于构件的软件开发技术(CBSD)等开始在软件开发中发挥出重要的作用.CBSD应用的成功主要体现在自底向上构造系统的方法上.目前,对SA的研究还缺乏一种自顶向下的构件动态组装方法,尤其是过程构件的组装.以工作流技术为基础,以基于Web应用为背景,研究了基于工作流引擎的构件组装方法.从业务过程的基本要素——业务对象、控制流和数据流入手,详细分析了这些要素在构件环境下的特点和交互模式,并以此为基础提出了一种基于工作流的引擎的过程构件组装体系结构.该体系结构中除了考虑常规的控制流驱动的构件组装外,还深入研究了文档型的数据流驱动的构件组装机制,能够为其他研究者将文档型工作流技术应用于软件构件组装提供借鉴和参考.     

软件体系结构与组件技术

在理论上，软件体系结构和基于组件的开发是理想的匹配；另一方面，软件体系结构是可重用软件组件的一种自然补充。只有通过实现体系结构模型，才能体现组件互操作性模型的所有优点。首先给出了大规模复杂分布式应用程序设计和进化方法选择中的关键因素；然后讨论软件组件技术与软件体系结构方法相互之间的要求，并探论了将软件体系结构与软件组件结合起来的可能途径。     

The Palladio component model for model-driven performance prediction

One aim of component-based software engineering (CBSE) is to enable the prediction of extra-functional properties, such as performance and reliability, utilising a well-defined composition theory. Nowadays, such theories and their accompanying prediction methods are still in a maturation stage. Several factors influencing extra-functional properties need additional research to be understood. A special problem in CBSE stems from its specific development process: Software components should be specified and implemented independently from their later context to enable reuse. Thus, extra-functional properties of components need to be specified in a parametric way to take different influencing factors like the hardware platform or the usage profile into account. Our approach uses the Palladio component model (PCM) to specify component-based software architectures in a parametric way. This model offers direct support of the CBSE development process by dividing the model creation among the developer roles. This paper presents our model and a simulation tool based on it, which is capable of making performance predictions. Within a case study, we show that the resulting prediction accuracy is sufficient to support the evaluation of architectural design decisions.     

基于组件的嵌入式软件开发方法

根据嵌入式软件的特点，提出一种以模型为中心、基于组件的嵌入式软件开发方法。它以动态数据流图为系统模型对嵌入式软件的功能和性能需求进行了描述，由此提供了强大的描述和分析能力；通过基于特定组件模型的实现结构和实现代码框架的自动生成，以DDF定义的系统可以被有效地分解为一系列独立的组件，合适的DDF调度算法一致地表示了系统组件的执行语义，使得并发开发的组件具有良好的可集成性。该方法充分考虑了嵌入式开发的特点，能有效地降低系统复杂性和支持系统组件的并发开发和复用，从而提高了开发效率并降低了开发成本。