对系统动态更新的探讨与设计

软件系统,特别是大型商业应用系统常常需要不断地更新,以满足新的需求,对于基于构件的软件系统,只需更换有关的构件,即可避免修改整个系统。但对于有些系统如分布式系统,如果为了更换构件而将系统关闭,将是不可想象的,会付出巨大的代价。动态地系统更新——软件即插即用将是更好的选择。另一方面,要实现真正的构件市场,构件必须不受配置特性的限制而能通用,这样重用构件就可以由专业化的第三方来生产。中间件的出现给软件即插即用提供了一定的支持,基于中间件的软件即插即用将是未来较为可行的方法。方法特点     

物联网中间件在公共领域中的应用

物联网的中间件是整个物联网系统的核心构件,它密切的关系着信息的安全可靠性,它在物联网的应用设备和感知设备之间有着很好的桥梁和纽带的作用.中间件的最大价值是为物联网的应用提供了有力的支持,从而大大提高了物联网的应用效果,提高对物联网应用的经济效益.从物联网在公共区域的应用为重点,对物联网中间件的发展做了一定的研究.     

支持上下文感知的构件适配模型研究

为了对普适环境下的构件化应用提供支持,扩展传统的构件适配技术,在上下文感知中间件的基础上,提出支持上下文感知的构件适配模型CACAM和构件适配算法CACA,实现对环境、用户上下文的动态感知和重配置。实验结果表明,该模型能够有效地实现普适计算环境下基于上下文感知的构件适配。     

分布式系统动态配置技术的研究与实现

动态配置技术用于系统运行时刻改变系统配置,从而满足分布式系统对在线演化的需求。如何保证系统一致性,并尽可能提高动态配置性能,是动态配置研究需要解决的关键问题。本文提出了行为一致性,并将系统一致性总结为行为一致性、构件状态一致性、应用状态一致性和引用一致性。通过扩展静止状态理论,本文提出了采用等待方式和阻塞方式驱动构件进入静止状态的算法,保证了行为一致性。通过分析动态配置意图,本文提出了保证系统一致性的动态配置算法,确定了采用等待方式和阻塞方式的动态配置场景,从而在严格保证行为一致性的前提下,尽可能地提高了动态配置性能。最后,本文基于 CCM 构件平台实现了动态配置平台。性能测试的结果表明,该平台可满足应用对性能的要求。     

池化资源技术在分布式Web系统中的应用

分析了数据库的连接、构件或中间件的加载与卸载次数和线程的重复使用等影响分布式Web系统性能的主要因素,运用“池化资源”技术解决了这一问题。论述了“池化资源”技术及其对提高分布式Web系统执行效率所起的作用,探讨了CGI,Web API,ASP和MTS等常用中间件对“池化资源”技术的支持,分析了不同中间件技术对Wel)系统执行效率的影响。应用实例表明,在Win2000平台上结合MTS中间件开发的分布式Web系统。对“池化资源”技术有很好的支持,可使系统的执行效率达到最高。     

普适计算环境下基于构件化中间件的上下文管理技术研究

上下文相关技术已经成为普适计算环境中用于应用服务的不可或缺的核心技术之一。对于基于构件的中间件来说,对高性能的上下文管理的需求更是必不可少,因为它构成了普适计算环境中构件适配和部署的重要基础。因此,在已有构件中间件的基础上,我们针对普适计算环境的特点提出了一种整体的上下文管理方法,将上下文管理集成在已有的构件化中间件中。应用表明,该方法能够更好地支持普适计算环境下上下文相关的构件化应用开发。     

动态配置机制及其在水利信息系统中的应用

动态配置是指在软件系统运行时动态地改变系统的配置项。基于构件的软件系统配置项涉及系统的构件组成、构件间的连接关系和构件的物理分布。根据支持软件系统动态配置的反射体系结构,建立了动态配置模型,分析了动态配置模型的构成要素,定义了动态配置模型的元数据,以保障运行时系统一致性为基础,构造了动态配置模型的元协议。最后,通过实例,分析了所提出的动态配置机制在水利信息系统软件功能动态配置中的应用。实践表明,基于反射的系统动态配置模型及其实现机制,能在水利信息系统中有效应用,为解决水利信息系统的资源动态配置、支持动态需求等问题,提供了可行的技术方案。     

基于软件体系结构的反射式中间件研究

Internet为分布应用提供了一种开放、动态的运行环境,这要求分布应用的主要基础设施中间件能够支持运行时查看并调整平台内部状态和行为,由此产生了反射式中间件.目前的反射式中间件研究与实践存在3个不足:注重系统局部或单个实体的反射而缺乏全局视图;注重中间件平台内部功能的反射,而对上层应用的反射不够;集中于CORBA平台,而对J2EE平台的反射性研究较少.介绍了一个反射式的J2EE应用服务器PKUAS.基于构件化的平台内部体系结构,PKUAS引入软件体系结构作为全局视图以实现反射体系对系统整体的表示和控制,作为J2EE应用服务器,PKUAS可反射底层平台以及上层EJB构件.同时,以PKUAS实时监控工具为例,探讨了如何利用基于软件体系结构的反射体系管理整个系统,并给出了PKUAS与其他几种反射式中间件的比较.该工作有效地解决了现阶段反射式中间件研究的不足,提高了反射式中间件的实用性.     

FORBus（基于CORBA的金融对象请求软总线）

FORBus是目前国内第一个遵循CORBA标准开发，并已实际投入金融关键业务领域应用的分布对象中间件产品。FORBus支持应用开发以“软总线 软构件”的模式来开发分布式应用系统，对基于构件的开发提供良好的支持。     

一种普适计算环境下自适应中间件

普适计算环境固有的内在复杂性对当前的基础软件提出了新的挑战,迫切需要一种具有感知和自适应能力的中间件.提出了一个由接口、框架和情境元模型组成的自适应中间件,给出了在CAR构件平台上的设计与实现.为获取构件信息和对外提供服务,接口元模型支持同步和异步接口.情境元模型在构件对象内建模情境信息,计算实体间以基于异步事件通知方式交互.框架元模型分类和管理构件,随着运行时计算环境的变化动态改变中间件的结构和行为.软件实体感知环境的变化,实体间以松耦合的方式交互,动态改变自身的结构和行为,满足普适计算环境下的动态自适应需求.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.