MobiPADS: a reflective middleware for context-aware mobile computing

Traditionally, middleware technologies, such as CORBA, Java RMI, and Microsoft's DCOM, have provided a set of distributed computing services that essentially abstract the underlying network services to a monolithic "black box." In a mobile operating environment, the fundamental assumption of middleware abstracting a unified distributed service for all types of applications operating over a static network infrastructure is no longer valid. In particular, mobile applications are not able to leverage the benefits of adaptive computing to optimize its computation based on current contextual situations. In this paper, we introduce the Mobile Platform for Actively Deployable Service (MobiPADS) system. MobiPADS is designed to support context-aware processing by providing an executing platform to enable active service deployment and reconfiguration of the service composition in response to environments of varying contexts. Unlike most mobile middleware, MobiPADS supports dynamic adaptation at both the middleware and application layers to provide flexible configuration of resources to optimize the operations of mobile applications. Within the MobiPADS system, services (known as mobilets) are configured as chained service objects to provide augmented services to the underlying mobile applications so as to alleviate the adverse conditions of a wireless environment.     

An efficient model-based methodology for developing device-independent mobile applications

Current methodologies for developing mobile applications are mostly based on the application programming interfaces (APIs) offered by the native platform. Hence, most solutions are characterized by a low portability and/or reusability. In this paper, we propose a novel methodology based on a declarative and device-independent approach for developing event-driven mobile applications. The methodology relies on: (i) an abstract mobile device based on the user interface markup language; (ii) a content adaptation mechanism based on user preferences; (iii) a context adaptation mechanism based on a standardized context of delivery; (iv) a uniform set of client-side APIs based on an interface object model; (v) an efficient transformational model.More specifically, in the design phase, the application is modeled as platform-independent on the abstract mobile device. In the execution phase, the application is automatically tailored to the specific platform on the basis of the content and context adaptation mechanisms. We describe the analysis, design and implementation of a framework, called MODIF, which supports the proposed methodology, and show its application to the development of both business and consumer real-world applications on Apple iPhone? and Google Android? mobile devices. Finally, we discuss how the experience of using MODIF highlights the quality of the methodology in terms of automation of the lifecycle, expressiveness and readability of the representation, efficiency of the compilation/interpretation, fast learning curve and predictability.     

CADeComp: Context-aware deployment of component-based applications

The expansion of wireless communication and mobile hand-held devices makes it possible to deploy a broad range of applications on mobile terminals such as PDAs and mobile phones. The constant context changes of mobile users oblige them to carry out many deployment tasks of the same application in order to obtain an application whose configuration satisfies the context requirements. The difficulty and the frequency of these deployment tasks led us to study the deployment in a mobile environment and to look for a solution for the automation of the deployment adaptation to the context. This paper studies the deployment sensitivity to the context in order to identify the variable deployment parameters and to analyze the impact of the deployment adaptation on the production life cycle of applications. The contribution made by this paper consists in an innovative middleware entity called Context-Aware Deployment of COMPonents (CADeComp), which can be plugged into existing middleware deployment services. CADeComp defines a flexible data model that facilitates the tasks of component producers and application assemblers by allowing them to specify the meta-information required to adapt the deployment to the context. The advantage of CADeComp is that it is based on reliable adaptive mechanisms that are defined by a platform-independent model according to the MDA approach. We propose a mapping of the CADeComp model to CCM. CADeComp was implemented and evaluated on this platform.     

一种支持自适应程序设计的移动机器人中间件

机器人控制中间件是软件中间件设计研究领域的一个热点.为了开发一种支持自适应程序设计的移动机器人中间件平台,首先提出这种中间件平台需要满足的设计要求:跨底层硬件平台、保证服务质量以及具备一定的自适应能力.从Java虚拟机的移植、服务质量表现形式的选择、自适应机制及SCC(Sensor/Compute/Control)设计结构的应用4个方面来阐述此中间件平台的设计思路和开发过程.最后,通过真实实验的数据对比,说明此中间件可为移动机器人程序的有效开发提供服务质量保证.     

A comprehensive solution for application‐level adaptation

Driven by the emergence of mobile and pervasive computing there is a growing demand for context‐aware software systems that can dynamically adapt to their run‐time environment. We present the results of project MADAM that has delivered a comprehensive solution for the development and operation of context‐aware, self‐adaptive applications. The main contributions of MADAM are (a) a sophisticated middleware that supports the dynamic adaptation of component‐based applications, and (b) an innovative model‐driven development methodology that is based on abstract adaptation models and corresponding model‐to‐code transformations. MADAM has demonstrated the viability of a general, integrated approach to application‐level adaptation. We discuss our experiences with two real‐world case studies that were built using the MADAM approach. Copyright © 2008 John Wiley & Sons, Ltd.     

Providing user context for mobile and social networking applications

The processing capabilities of mobile devices coupled with portable and wearable sensors provide the basis for new context-aware services and applications tailored to the user environment and daily activities. In this article, we describe the approach developed within the UPCASE project, which makes use of sensors available in the mobile device as well as sensors externally connected via Bluetooth to provide user contexts. We describe the system architecture from sensor data acquisition to feature extraction, context inference and the publication of context information in web-centered servers that support well-known social networking services. In the current prototype, context inference is based on decision trees to learn and to identify contexts dynamically at run-time, but the middleware allows the integration of different inference engines if necessary. Experimental results in a real-world setting suggest that the proposed solution is a promising approach to provide user context to local mobile applications as well as to network-level applications such as social networking services.     

CARISMA: context-aware reflective middleware system for mobile applications

Mobile devices, such as mobile phones and personal digital assistants, have gained wide-spread popularity. These devices will increasingly be networked, thus enabling the construction of distributed applications that have to adapt to changes in context, such as variations in network bandwidth, battery power, connectivity, reachability of services and hosts, etc. In this paper, we describe CARISMA, a mobile computing middleware which exploits the principle of reflection to enhance the construction of adaptive and context-aware mobile applications. The middleware provides software engineers with primitives to describe how context changes should be handled using policies. These policies may conflict. We classify the different types of conflicts that may arise in mobile computing and argue that conflicts cannot be resolved statically at the time applications are designed, but, rather, need to be resolved at execution time. We demonstrate a method by which policy conflicts can be handled; this method uses a microeconomic approach that relies on a particular type of sealed-bid auction. We describe how this method is implemented in the CARISMA middleware architecture and sketch a distributed context-aware application for mobile devices to illustrate how the method works in practice. We show, by way of a systematic performance evaluation, that conflict resolution does not imply undue overheads, before comparing our research to related work and concluding the paper.     

Utilizing architectural styles to enhance the adaptation support of middleware platforms

ContextModern middleware platforms provide the applications deployed on top of them with facilities for their adaptation. However, the level of adaptation support provided by the state-of-the-art middleware solutions is often limited to dynamically loading and off-loading of software components. Therefore, it is left to the application developers to handle the details of change such that the system’s consistency is not jeopardized.ObjectiveWe aim to change the status quo by providing the middleware facilities necessary to ensure the consistency of software after adaptation. We would like these facilities to be reusable across different applications, such that the middleware can streamline the process of achieving safe adaptation.MethodOur approach addresses the current shortcomings by utilizing the information encoded in a software system’s architectural style. This information drives the development of reusable adaptation patterns. The patterns specify both the exact sequence of changes and the time at which those changes need to occur. We use the patterns to provide advanced adaptation support on top of an existing architectural middleware platform.ResultsOur experience shows the feasibility of deriving detailed adaptation patterns for several architectural styles. Applying the middleware to adapt two real-world software systems shows the approach is effective in consistently adapting these systems without jeopardizing their consistency.ConclusionWe conclude the approach is effective in alleviating the application developers from the responsibility of managing the adaptation process at the application-level. Moreover, we believe this study provides the foundation for changing the way adaptation support is realized in middleware solutions.     

Efficient profile aggregation and policy evaluation in a middleware for adaptive mobile applications

There is a large consensus on the need for a middleware to efficiently support adaptation in pervasive and mobile computing. Advanced forms of adaptation require the aggregation of context data and the evaluation of policy rules that are typically provided by multiple sources. This paper addresses the problem of designing the reasoning core of a middleware that supports these tasks, while guaranteeing very low response times as required by mobile applications. Technically, the paper presents strategies to deal with conflicting rules, algorithms that implement the strategies, and algorithms that detect and solve potential rule cycles. A detailed experimental analysis supports the theoretical results and shows the applicability of the resulting middleware in large-scale applications.     

基于上下文感知移动中间件的研究与设计

移动环境和设备的限制,给移动开发带来了挑战。移动中间件能够为移动应用开发提供了一个很好的基础平台。叙述了自适应机制在中间件层实现的必要性,分析了传统面向对象中间件应用在移动计算环境中的不足。根据移动应用的需求,提出了一个基于上下文感知的移动中间件体系结构。     

Using architecture models for runtime adaptability

Every software system has architecture. The architecture strongly influences the software system's properties, including maintainability and runtime properties such as performance and reliability. By describing the architecture in models, we can make the architecture explicit. Developers typically use software architecture models at design time to capture the significant decisions about a software system's organization and to describe and establish a common understanding about the system's abstract properties. In the MADAM (mobility- and adaptation-enabling middleware) project, we aim to facilitate adaptive application development for mobile computing. We follow an architecture-centric approach where we represent architecture models at runtime to allow generic middleware components to reason about and control adaptation.     

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。     

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.     

FollowMeLite：用于普适计算的轻量级中间件平台

普适计算的目标是让环境和计算资源紧密结合，以便更好地为人类服务。为达到这一目标，移动设备和嵌入式设备构成了环境中计算资源的重要组成部分。然而，由于移动设备和嵌入式设备的计算资源有限，网络连接的多样性和不稳定性以及软硬件的异构性，开发用于这些设备的上下文感知应用复杂并且费时，其根本原因是缺乏一个统一的平台支持。为解决这一问题，我们提出了一种用于普适计算的轻量级中间件平台，叫做FollowMeLite。FollowMeLite是整个FollowMe普适计算基础结构中的一部分。它构建在OSGi之上，集成了基于本体的上下文模型和基于工作流的应用模型以及用于适应多种网络连接的通讯服务。通过部署不同的组件模块，FollowMeLite可以方便的适用于多种应用环境。     

无线传感器网络中间件研究进展

无线传感器网络作为一种新兴的技术,受到了学术界和工业界的广泛关注.然而随着传感器网络及其应用的发展,系统的复杂性也随之增加,与传统网络相比无限传感器网络又具有其独特的特征,使得无线传感器网络的程序开发变得更加困难.中间件提供了一个编程抽象,方便了应用程序的开发,缩减了应用程序和底层设备的间隙.针对无线传感器网络的特点,分析了无线传感器网络中间件设计面临的问题,对有关设计方法进行了分类评述,并对几种典型中间件进行了比较,最后从通信范式、QoS支持和安全等方面提出了一些改进思路.     

OpenCOPI: middleware integration for Ubiquitous Computing

In this paper, we present OpenCOPI (Open COntext Platform Integration), a Service-Oriented Architecture-based middleware platform that supports the integration of services provided by distinct sources, ranging from services offered by simple systems to more complex services provided by context-provision middleware. OpenCOPI offers selection and composition mechanisms to, respectively, select and compose services provided by different sources, considering applications of both Quality of Service and Quality of Context requirements. It also offers an adaptation mechanism that enables to adapt the application execution due to service failures, service quality fluctuation and user mobility. OpenCOPI allows the definition of applications in a higher abstraction level by the specification of a semantic workflow that contains abstract activities. This paper illustrates the use of OpenCOPI in an application from the Gas & Oil Industry and it also shows the evaluation of the main mechanisms of OpenCOPI: the service selection, composition, adaptation and workflow execution.     

Mobile data collection in sensor networks: The TinyLime middleware

In this paper we describe TinyLime, a novel middleware for wireless sensor networks that departs from the traditional setting where sensor data is collected by a central monitoring station, and enables instead multiple mobile monitoring stations to access the sensors in their proximity and share the collected data through wireless links. This intrinsically context-aware setting is demanded by applications where the sensors are sparse and possibly isolated, and where on-site, location-dependent data collection is required. An extension of the Lime middleware for mobile ad hoc networks, TinyLime makes sensor data available through a tuple space interface, providing the illusion of shared memory between applications and sensors. Data aggregation capabilities and a power-savvy architecture complete the middleware features. The paper presents the model and application programming interface of TinyLime, together with its implementation for the Crossbow MICA2 sensor platform.     

Programmable context awareness framework

Context-awareness enables applications to provide end-users with a richer experience by enhancing their interactions with contextual information. Several frameworks have already been proposed to simplify the development of context-aware applications. These frameworks are focused on provisioning context data and on providing common semantics, definitions and representations of these context data. They assume that applications share the same semantic, which limits the range of use cases where a framework can be used, as that assumption induces a strong coupling between context management and application logic. This article proposes a framework that decouples context management from application business logic. The aim is to reduce the overhead on applications that run on resource-limited devices while still providing mechanisms to support context-awareness and behavior adaptation. The article presents an innovative approach that involves third-parties in context processing definition by structuring it using atomic functions. These functions can be designed by third-party developers using an XML-based programming language. Its implementation and evaluation demonstrates the benefits, in terms of flexibility, of using proven design patterns from software engineering for developing context-aware application.