An Adaptive Middleware for Context-Sensitive Communications for Real-Time Applications in Ubiquitous Computing Environments

Context-sensitivity is an important expected capability in applications in ubiquitous computing (ubicomp) environments. These applications need to use different contextual information from the user, host device, on board sensors, network, and the ambient environments to systematically adapt their actions. In addition, some context-sensitive applications may use specific contextual conditions to trigger impromptu and possibly short-lived interactions with applications in other devices. This property, referred to as context-sensitive or context-aware communications, allows applications to form short-range mobile ad hoc networks consisting of mobile and stationary devices, sensors, and other computing resources. Real-time applications, especially those having reactive behavior, running on embedded devices and requiring context-sensitive communications support, pose new challenges related to systematic representation of specific contexts, associations of contexts with real-time actions, timely context data collection and propagation, and transparent context-sensitive connection establishment. An object-based middleware can be effective to meet these challenges if such a middleware can provide a well-defined development framework as well as lightweight runtime services. In this paper, an adaptive and object-based middleware, called reconfigurable context-sensitive middleware (RCSM) is presented to facilitate context-sensitive communications in ubicomp environments. To facilitates context-sensitive communications, RCSM provides a context-aware interface definition language for specifying context-sensitive interfaces of real-time objects, an object container framework for generating interfaces-specific context-analyzers, and a context-sensitive object request broker for context-sensitive object discovery and impromptu connection management. RCSM is adaptive in the sense that depending on the context-sensitive behavior of the applications, it adapts its object discovery and connection management mechanisms.     

面向普适计算的动态自适应中间件模型

为了提高普适计算系统的开发效率, 设计了一个基于OSGi框架的动态普适计算中间件模型. 该中间件模型以OSGi框架为基础, 建立移动管理器管理用户和服务的移动, 利用上下文管理器来管理上下文, 动态调整自己的行为, 支持上下文感知应用. 通过标准的接口实现各种异构普适设备间的互操作性. 实验结果表明该中间件能够满足通用普适计算环境的要求, 对于普适计算系统的开发具有一定的借鉴意义.     

OnceRMF:一种效用驱动的中间件资源管理框架

中间件资源管理是保障Web应用性能的重要手段,然而目前系统驱动和业务驱动两种主要的资源管理视角没有在概念上取得统一,相关研究成果主要针对特定的资源,难以实施整体性的资源管理优化。针对中间件资源特征提出了一种层次化的中间件资源空间模型;通过效用函数实现系统驱动与业务驱动的协同资源管理,形成了一种效用驱动的中间件资源管理框架OnceRMF。通过仿真实验结果验证了OnceRMF的有效性。     

基于SOA与资源即插即用的RFID中间件

融合各种通信网络异构性的无线泛在网将成为网络发展的必然趋势。为实现无线业务的泛在化,提出一种基于SOA与资源即插即用功能的泛在网RFID中间件架构,使其能在未来的基于Web的无线泛在业务环境体系架构中完成智能感知设备资源的即插即用特性。介绍了该架构逻辑框架中各部分的功能与实现方法,并通过具体应用系统验证了该架构不仅可以解决RFID设备与应用系统之间的紧耦合问题,而且能够实现单一物理设备服务多种业务应用的需求。     

HITGRID:基于动态规划技术的网格任务调度中间件

随着计算规模不断扩大,人们对并行计算调度的性能要求也不断提高。网格技术的出现,解决了计算资源的共享性、异构性、规模可扩展性、鲁棒性以及安全性等方面的问题,但同时也在资源调度方面带来了新的挑战。HITGRID是一个基于Globus网格工具平台上的网格调度中间件,它接收用户提交的计算任务,针对用户对计算资源提出的要求,在网格环境中查找符合条件的资源进行调度。文中讨论了将NWS预测技术封装为标准网格资源信息的方法,以及资源调度的性能模型,给出了调度中资源选择的策略。最后通过一个计算大规模N体问题的实例表明笔者的工作是有成效的。     

面向普适环境的上下文感知中间件研究

针对普适环境下上下文感知计算需求,引入广义模型化理论,建立了一种面向通用环境资源的上下文信息数据模型;在此基础上,提出了上下文感知中间件体系框架,并详细阐述了其构件化的实施方案。该中间件平台的上下文获取层能够封装各类感知器捕获的资源信息,中间处理层负责信息的管理、推理和聚合,基于门面模式的上下文访问层提供同步和异步相结合的上下文信息统一访问入口。通过实验测试了平台的时间损耗,表明该中间件可提供通用的上下文感知服务且具有较好的系统性能。     

基于上下文感知的普适服务框架

为了更好地适应用户的个性化需求和普适计算环境的特征,提出一种基于上下文感知的普适服务框架。该框架包括服务呈现层、服务管理层、服务提供层和上下文感知层。通过基于社区的服务管理方式来屏蔽普适计算环境中服务的异构性、分布性,动态地感知与当前计算环境和用户活动相关的上下文信息,采用基于上下文的服务推荐机制为用户提供个性化的服务,从而更好地适应人的意图和环境 因素。     

MCSM:一种基于移动设备的上下文感知中间件

提出一种针对移动设备的上下文感知中间件MCSM(Mobile Context Sensing Middleware).MCSM可以动态地感知当前移动设备的内外部计算环境及用户活动等上下文信息,并以统一的接口将感知到的上下文数据提供给上层应用程序.为了克服外部传感器数据的高异构性,MCSM采用了一种基于XML的上下文数据描述语言CDDL.基于MCSM的原型系统表明,MCSM具有良好的运行效率和可扩展性,并可显著提高上下文应用程序的开发效率.     

基于上下文的自适应构件化中间件模型

由于普适计算环境越来越复杂对自适应软件开发要求越来越高,为了对普适计算环境下的自适应和构件化应用提供支持,提出了一种适用于普适计算环境的基于上下文的自适应构件化的CBACM中间件模型。最后,仿真实验结果表明了CBACM模型较传统中间件在自适应成功率、资源消耗和响应时间方面的优势。     

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.     

改进的网络服务资源定位算法

针对对等网络中Chord模型的不足,以网络资源定位为研究对象,将减少资源定位的等待时间作为改进目标,在分析现有解决思路和方法的基础上,引入双向路由机制和考虑后继节点列表的路由选择机制。针对模型的改变,对原有路由方法、稳定机制和路由信息的维护方法进行修改,并加以实现。模拟实验证明,与原算法相比,该改进资源定位算法减少了资源定位的等待时间。     

On Developing Distributed Middleware Services for QoS- and Criticality-Based Resource Negotiation and Adaptation

The Global Resource Management System (GRMS) provides middleware services for QoS- and criticality-based resource negotiation and adaptation across heterogeneous computing nodes and communication networks. This paper presents GRMS's design, prototyping, and performance evaluation. We introduce GRMS design principles and two key concepts unified resource model and ripple scheduling--and describe our architectural design based on these concepts. Further, we present a decentralized end-to-end two-phase negotiation and adaptation protocol with the functionality of distributed, dynamic QoS adjustment and stream preemption. We discuss GRMS's system prototyping and lessons learned and report our experimentation and simulation results, providing insights into design and implementation of a middleware-based distributed resource management system.     

Seamless User-Level Handoff in Ubiquitous Multimedia Service Delivery

Advancing mobile computing technologies are enabling ubiquitous personal computing environment. In this paper, we focus on an important problem in such environment: user mobility. In the case of user mobility, a user is free to access his/her personalized service at anytime, anywhere, through any possible mobile/fixed devices. Providing mobility support in this scenario poses a series of challenges. The most essential problem is to preserve the user's access to the same service despite changes of the accessing host or service provider. Existing system-level mobility solutions are insufficient to address this issue since it is not aware of the application semantics. On the other hand, making each application to be mobility-aware will greatly increase the development overhead. We argue that the middleware layer is the best place to address this problem. On one hand, it is aware of application semantics. On the other hand, by building application-neutral mobility functions in the middleware layer, we eliminate the need to make each application mobility-aware. In this paper, we design a middleware framework to support user mobility in the ubiquitous computing environment. Its major mobility functions include user-level handoff management and service instantiation across heterogeneous computing platforms. We validate the major mobility functions using our prototype middleware system, and test them on two multimedia applications (Mobile Video Player and Mobile Audio Player). To maximally approximate the real-world user-mobility scenario, we have conducted experiments on a variety of computing platforms and communication paradigms, ranging from T1-connected high-end PC to handheld devices with wireless networks. The results show that our middleware framework is able to provide efficient user mobility support in the heterogeneous computing environment.     

普适计算中间件技术的研究与进展

当前,普适计算已经成为计算机科学中一个极具活力和影响力的研究领域。普适计算环境规模很大并且具有高度异构性,如网络架构的异构性、硬件平台的异构性、操作系统的异构性、应用服务的异构性等,而普适计算中间件技术可以解决异构性和跨平台特征,提供不同服务的集成应用,因此成为普适计算中的一个研究热点。基于此,本文对于目前国外关于普适计算中间件技术的研究现状做了一个总结;通过分析和比较,给出了普适计算中间件的设计原则;探讨了普适计算中间件技术的未来发展方向。     

面向资源广域分布环境的数据复制定位

在资源广域分布的环境中，数据复制和定位是提高数据访问性能的关键技术之一。该文提出了一种分布式、自适应复制定位机制(ALM)，该机制基于复制定位信息分发和网络缓存思想，采用分层的分布式复制目录系统和软状态协议实现。其中，复制目录系统分布存储复制定位信息，软状态协议分发复制定位信息及其改变。因此，ALM具有很好的分布性和自适应性。ALM在复制目录的设计中引入了Web缓存的功能，使得ALM较其它机制具有更广泛的适用性。     

嵌入式实时中间件QoS体系结构的分析与实现

本文在分析现有嵌入式实时中间件的基础上,给出了一种随环境动态变化而调整服务策略的分布式嵌入式实时中间件QoS体系结构,并分析了两种保证服务质量的资源管理策略。     

面向开放移动网络环境的新一代中间件技术研究

结合现有网络计算环境的特点,对适用于开放、移动网络环境的新一代中间件技术进行了研究。在分析今天网络环境关键特征的基础上,提出了新一代中间件系统需要满足的技术需求;从所针对的问题角度对新一代中间件系统面临的主要挑战进行了详细的讨论,包括上下文感知、环境自适应、开放式协作、服务发现和普适互操作等,并给出了一些解决方案。     

动态网格环境下资源发现的研究

网格中资源是动态变化的,资源状态的不断改变,使得资源发现变得更为复杂。文中提出了一种适合于三层P2P结构的资源发现的算法,它利用复制技术缩短查找的时间,节省内存开销,并给出了消息传播过程中所使用的一些协议,解决了传播过程中存在的问题,更好的适应了网格资源的动态变化。     

动态环境下网格资源发现的研究

一个典型的网格系统包括大量的资源,网格中的资源必须先被识别,然后才能应用,因此资源发现是网格环境中一个重要的问题。文中提出一个P2P系统,该系统能够检索和发现网格资源,并给网格资源定义了一些属性,在这些属性范围内,系统能够检索资源,从而能够满足任意范围内资源的需要。大量的实验表明该系统具有良好的伸缩性,更好的适应了网格资源的动态变化。     

The FUSE Platform: Supporting Ubiquitous Collaboration Within Diverse Mobile Environments

The recent proliferation of heterogeneous computing devices and wireless network technology presents new opportunities for Computer Supported Cooperative Work (CSCW). One emergent paradigm is that of ubiquitous collaboration, which provides widespread access to shared services through a variety of interactive devices, irrespective of whether individuals are mobile or deskbound. However, developing groupware that is interoperable across diverse, often mobile, environments can be difficult and costly. The fundamental issue is that current support infrastructures, which will meet the requirements for multi-user application development, are not operable within emerging ubiquitous settings. This paper explores this problem and presents a generic platform that promotes new forms of collaboration through mobility and ever-present computing services. The developed platform seeks to provide a wide range of collaborative services to a very diverse set of devices by adapting and extending existing middleware technologies.