基于构件化的软件产品开发研究

为了满足软件产品的开发对生产质量和开发周期提出的更高要求,阐述了标准化工作中的模块化在软件产品构件化开发中的重要性,回顾了基于构件的软件开发方式的发展历程,提出了基于构件的软件开发方式和相关的实施案例。通过构件化的开发方法,为企业提高了软件产品质量,缩短了产品上市的周期,取得了良好的经济效益。     

Towards a General Component Model for Web-Based Applications

The cost effective development of web applications is perhaps one of the most challenging areas of software engineering today. Not only are the problems to be solved, and the solution technologies to be used, in web application development among the most rapidly changing in the software industry, but the business pressures of cost, quality and time-to-market are among the most extreme. Web application development therefore has potentially the most to gain from software reuse approaches that can offer a greater return on development time than traditional approaches. However, simply combining ideas from these reuse paradigms and traditional web development technologies in ad-hoc ways will not result in sustainable improvements. In this paper we describe a systematic way of combining the benefits of component-based development and model driven architectures, two important reuse approaches, to support the cost effective development and maintenance of web applications. After first defining a suitably abstract component-model, the paper explains how component architectures can be systematically and rigorously modeled using UML. It then describes a powerful technique, known as stratification, for separating the various cross cutting aspects of a web application such that a suitable platform specific architecture can be traceably generated. Finally, the paper introduces a technique for increasing the trustworthiness of components by giving them the capability to check their deployment environment at run-time.     

Towards a visual approach for component-based software development

The ever increasing emphasis on distributed systems has led to advances in the client/server model and the emergence of component-based software development as an important paradigm in software engineering. Along with the new computer technologies it is necessary to reuse legacy code. Approaches to application development over, for example, the Internet are important if this is to be successful. This paper examines these issues and argues that incorporating the ideas of the component-based approach and reuse can significantly assist the application software developer. It demonstrates an approach through the development of an interactive/visual environment for component-based assembly.     

基于模型的构件软件修改影响分析

基于构件的软件构建方法目前被广泛使用在软件开发中,用于减少软件开发的工程成本和加快软件开发进度.面向构件的系统主要由第三方提供的可重用构件或者内建的可重用构件组成,因此,系统的质量好坏和维护的难易程度依赖于构件的品质.一个软件修改会给其他构件甚至整个系统带来影响,而修改影响分析是控制和消除这类影响的有效手段.然而,现有的研究很少涉及构件软件的修改影响分析,尤其缺少对系统层面的修改影响分析研究.提出了一种基于模型的系统化修改影响分析方法,该方法的基本思路是:首先提出构件及系统层面的修改影响分析模型,然后根据分析模型分别从构件和系统两个层面对构件软件修改前后的版本进行修改识别,并且利用“防火墙”方法进行影响分析.理论分析和实验结果表明,该方法是可行的,也是有效的.     

基于组件的飞行控制系统软件设计方法

该文分析了无人直升机飞行控制系统软件实现要求。提出基于组件的程序设计方法开发此类软件，充分考虑模块的重用性，以组件为核心，每一组件单独开发与测试，然后按照一定的集成规则，分层、渐进地开发整个系统。组件之间的通信通过事件机制来实现，使得子系统之间的耦合减小，并且增加了系统的可靠性、灵活性和重用性。最后开发了飞行控制系统设计中的模型、参考模型和逆模型组件，并进行了仿真验证，结果表明这种设计方法将大大简化复杂控制系统的软件设计，方便系统软件的工程实现。     

方面化构件模型及其组装方法

结合基于构件开发的软件工程思想和面向方面开发的优点，提出了方面化构件模型，探讨了利用AspectJ中的方面以及动态代理实现核心模块构件和全局性约束构件的组装方法。使得构件在组装过程中获得了透明性、可重用性和灵活性。     

Component-based software version management based on a Component-Interface Dependency Matrix

As much component-based software is developed, a software configuration management (SCM) tool for component-based software is necessary. In this paper, we propose a version management mechanism for impact analysis while components are upgraded. We separately version the components and interfaces based on a Component-Interface Dependency Matrix (CIDM), and analyze impacts according to their dependency relationship. The result of our simulation shows that CIDM is capable of managing large numbers of components without impedance mismatch. In addition, in a well-designed software system, using CIDM to analyze impacts can save resources in the software development phase.     

Built-In Contract Testing in Component Integration Testing

Assembling new software systems from prefabricated components is an attractive alternative to traditional software engineering practices which promises to increase reuse and reduce development costs. However, these benefits will only occur if separately developed components can be made to work effectively together with reasonable effort. Lengthy and costly in-situ verification and acceptance testing directly undermines the benefits of independent component fabrication and late system integration. This position paper outlines and introduces an approach for reducing manual system verification effort by equipping components with the ability to check their execution environments at run-time. When deployed in new systems, built-in tester components check the contract-compliance of their server components, including the run-time system, and thus automatically verify their ability to fulfill their own obligations. This comprises functional/behavioural contracts as well as quality-of-service contracts between individual components. Enhancing traditional component-based development methods with built-in contract testing in this way reduces the costs associated with component assembly, and thus makes the “plug-and-play” vision of component-based development closer to practical reality.     

The Economics of Component-Based Development

Software components have been championed because they can be used to shorten a system's software development cycle and therefore lower its development costs. As this column explains, lower development expenses are just one of the many economic benefits that can be realized with component-based development.     

Reusability of model components for environmental simulation – Case studies for integrated coastal zone management

Model constructs in environmental models are seldom reused beyond the project lifetime or in other modelling studies. A library of reusable model components could facilitate the maintenance of existing models and make the design of new models more efficient. Although component-based design is the common standard in software engineering and manufacturing few examples are yet found in environmental science. The multi-disciplinary project SPICOSA used a common, component-based simulation framework for environmental modelling, based on 18 case studies through Europe. The development of high-quality model components with potential for reuse turned out to be a challenge despite of the guidelines and tutorial examples provided. Well-designed components are of appropriate granularity, encapsulated, with a limited use of connectors and proper data handling. Ultimately, the success of a model library depends on a sufficient set of quality components with complementary functionalities, a framework for quality control, and support of the environmental modelling community.     

A generic approach for developing process-level hydrologic modeling components

Component software architectures offer an alternative approach for building large, complex hydrologic modeling systems. In contrast to more traditional software paradigms (i.e. procedural or object-oriented approaches), using component-based approaches allows individuals to construct autonomous modeling units that can be linked together through shared boundary conditions during a simulation run. One of the challenges in component-based modeling is designing a simple yet robust means for authoring model components. We address this challenge by presenting an approach for efficiently creating standards-based, process-level hydrologic modeling components. Using this approach, a hydrologic process is implemented as a modeling component by (1) authoring a configuration file that defines the properties of the component and (2) creating a class with three methods that define the pre-run, runtime, and post-run behavior of the modeling component. We present the design and implementation of this approach, which we call the Simple Model Wrapper (SMW), and demonstrate how it can be applied to create an Open Modeling Interface (OpenMI)-compliant modeling component for a basic hydrologic process.     

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UML的构件可重用性度量方法

随着基于构件软件开发实践的深入,构件的质量将影响到最终的软件质量,但目前缺乏对构件在实际应用中有效的评价模型.基于Perry所提出的度量方法,给出了应用在UML中的度量模型,并且设计实现了对应的度量工具,以便构件使用者能够在实际开发应用中找出合适的构件.     

Three from Harvard Business Press

Abstract

Software components have been championed because they can be used to shorten a system's software development cycle and therefore lower its development costs. As this column explains, lower development expenses are just one of the many economic benefits that can be realized with component-based development.     

基于体系结构的软件可靠性模型的统一框架

随着面向对象技术的发展,传统的黑盒方法已无法建模新型的基于构件的软件系统,为此当前的研究工作集中于对基于体系结构的软件可靠性模型的开发。但目前极少有研究工作把它们放在一个统一的框架中进行全面的分析比较。基于此本文提出一个基于体系结构的软件可靠性模型的统一框架:以基于状态的模型为核心,实现了所有基于体系结构模型的统一,并通过实例对该框架中的模型进行说明,详细讨论框架中每类模型的输入参数的估计方法及模型适用于软件生命周期的哪一阶段。     

Component behavior-based adaptation in embedded software

Several models of computation have been used in software development approaches. The specialization of the existing models makes them suitable to specific application domains. Nevertheless, when there is no solution for applications at hand, heterogeneous models have been used. Within this context, this paper discusses a heterogeneous model called extended dataflow with a focus on component-based design. The emphasis lies on the dynamics of the components, including the way they interact with each other, their behavioral modeling, and flow of control. The main objective is to provide mechanisms for supporting both the ability of the run-time environment to safely dispatch tasks and the ability of components to adapt their interfaces. This paper focuses on embedded software. The purpose of the mechanisms we have been working on is to improve robustness while promoting component-based design. An adaptive application involving digital filters is used to illustrate our approach.     

一种基于嵌入式软件构件管理方法

构件化软件开发的最终目的是希望软件像传统产品一样能在生产线上生产出来。软件最终由软件框架来实现,一个良好的软件框架应该能够将设计结果尽量保存下来,同时可以灵活更换和重用软件部件。研究构件化的软件框架对构件化的开发技术在嵌入式实时软件开发中迅速普及具有最直接的推动作用。对嵌入式控制系统嵌入软件构件框架进行了深入研究,完成了框架中的数据管理和构件调度机制等内容,验证了该源码构件模型在嵌入式控制软件领域中的可用性。     

构件式建模方法在系统建模中的应用研究

为了使系统级建模过程工程化,提高模型构件的重用度,针对建模的实现过程,提出了通用的建模模式和构件式建模方法。将数据抽象、信号原语、异步并发机制处理等过程归纳为建模模式,并建立了典型的软硬件构件模型以便建模时重用,方便了快速建模和模型构件的重用;以无线接入系统为例,运用构件式建模方法建立了其系统模型,仿真分析了WLAN网络环境下站点数等参数对有效吞吐量的影响。实践表明,构件式建模方法能加快系统的建模过程,有助于实现建模过程的工程化。     

一种支持普适计算的构件管理框架:LCF

普适计算的发展需要新型的软件结构与之相适应,构件化技术就是一种较好的方法。普适计算强调人、计算机以及环境的相互融合,这就对构件化技术提出了新的挑战:如何对管理各种计算设备、如何主动发现构件、如何解决构件的异构、如何实现构件间协调机制、如何保证访问的安全性等。文章着重探讨和分析了这一系列问题,并且提出了一种支持普适计算的构件管理框架LCF。     

基于有限状态自动机的构件化软件集成测试方法

构件技术及其相应规范的出现带来了构件化软件时代。可是构件化软件固有的特点向传统的程序分析测试技术提出了一个尖锐的问题：构件的开发者独立开发和测试了构件，而使用构件的用户在无法访问到构件源代码的前提下如何对构件化系统进行充分测试？在观测构造理论基础上构造了一种基于有限状态自动机，并可验证构件化软件行为的测试方法。通过实验验证了其有效性。