基于XML和Reactor模式的消息中间件的设计

在复杂的分布式计算环境中,中间件已经成为分布式计算应用的关键性部件。本文设计实现了一个基于消息队列的消息中间件系统,用于集成分布式应用,提供可靠的和松耦合的通信服务。系统采用XML定义消息,统一了消息格式;采用Reactor设计模式,提高了系统的模块化和可重用性。     

Beyond ubiquitous computing: The Malaysian HoneyBee project for Innovative Digital Economy

In the proposed advanced computing environment, known as the HoneyBee Platform, various computing devices using single or multiple interfaces and technologies/standards need to communicate and cooperate efficiently with a certain level of security and safety measures. These computing devices may be supported by different types of operating systems with different features and levels of security support. In order to ensure that all operations within the environment can be carried out seamlessly in an ad-hoc manner, there is a need for a common mobile platform to be developed. The purpose of this long-term project is to investigate and implement a new functional layered model of the common mobile platform with secured and trusted ensemble computing architecture for an innovative Digital Economic Environment in the Malaysian context. This mobile platform includes a lightweight operating system to provide a common virtual environment, a middleware for providing basic functionalities of routing, resource and network management, as well as to provide security, privacy and a trusted environment. A generic application programming interface is provided for application developers to access underlying resources. The aim is for the developed platform to act as the building block for an ensemble environment, upon which higher level applications could be built. Considered as the most essential project in a series of related projects towards a more digital socio-economy in Malaysia, this article presents the design of the target computational platform as well as the conceptual framework for the HoneyBee project.     

A lightweight and distributed middleware to provide presence awareness in mobile ubiquitous systems

Several researchers have identified the need to count on presence awareness in ubiquitous systems that support mobile activities, particularly when these systems are used to perform loosely-coupled mobile work. In such a work style, mobile users conduct face-to-face on-demand interactions, therefore counting on awareness information about the position and availability of potential collaborators becomes mandatory for these applications. Most proposed solutions that provide user presence awareness involve centralized components, have reusability limitations, or simply address a part of that service. This article presents a lightweight and fully distributed middleware named Moware, which allows developers to embed presence awareness services in mobile ubiquitous systems in a simple way. The article also describes the Moware architecture, its main components and strategies used to deal with several aspects of the presence awareness support. These design strategies can be reused by software designers to provide presence awareness capabilities into middleware and specific software applications. Moware services were embedded in a mobile ubiquitous system that supports inspectors during the construction inspection process. The preliminary results indicate that the middleware was easy to use for developers, and its services were useful for the end-users.     

基于分布对象技术的移动中间件

基于JavaRMI技术的移动中间件存在一定程度的局限性。文中以中间件、分布对象计算和移动计算等相关领域的技术为背景,提出了基于分布对象技术的移动中间件MMDO(MobileMiddlewareBasedonDistributedObject),该体系结构包括:动态可定制的基础核心、通用移动Agent平台、异步消息服务、动态资源发现和移动用户安全注册。MMDO能够解决移动中间件研究存在的Java效率问题,同时拓展了移动服务,给移动应用提供更好的支撑环境。最后,给出仿真测试结果,证明了MMDO的有效性。     

The Esperanto Broker: a communication platform for nomadic computing systems

There is an increasing demand for middleware for nomadic computing applications. Owing to the inherent characteristics of such environments, these platforms have to address two fundamental issues: (i) device disconnections and the limitations of wireless networks may force users to experience short periods of service unavailability; and (ii) the complexity to design and develop next‐generation mobile computing applications. This paper proposes the Esperanto Broker (EB), a communication platform that addresses mobility issues via an integrated approach, i.e. at data‐link, network, and middleware levels. Decoupling interactions are achieved via a tuple‐space underlying infrastructure. To support developers with advanced services, the EB enhances the distributed objects computing model providing the abstraction for the communication paradigms standardized by the W3C. Esperanto applications can be modeled as sets of objects that are distributed over mobile devices, which communicate via remote method invocations (RMIs). RMIs natively implement pull and push models, in both one‐to‐one and one‐to‐many multiplicity. The paper focuses on the EB design issues, essential aspects of the implementation, and performance evaluations of the implemented prototype. Copyright © 2006 John Wiley & Sons, Ltd.     

基于FIPA架构的移动服务中间件的设计与实现

在有基站的移动计算中,移动终端和计算机网络服务器之间是一个多对多的应用关系,移动终端使用网络服务资源,服务器向移动终端组播异构信息是其典型应用.本文给出了基于FIPA架构的,跨平台的移动服务中间件解决方案,在介绍FI-PA发展现状的基础上,阐述了该中间件的实现技术和应用结构,以多代理技术实现了移动计算与SOA的结合,扩展了JADE架构的组播功能.     

Mobile agent middleware for mobile computing

Mobile computing requires an advanced infrastructure that integrates suitable support protocols, mechanisms, and tools. This mobility middleware should dynamically reallocate and trace mobile users and terminals and permit communication and coordination of mobile entities. In addition, open and untrusted environments must overcome system heterogeneity and grant the appropriate security level. Solutions to these issues require compliance with standards to interoperate with different systems and legacy components and a reliable security infrastructure based on standard cryptographic mechanisms and tools. Many proposals suggest using mobile agent technology middleware to address these issues. A mobile agent moves entities in execution together with code and achieved state, making it possible to upgrade distributed computing environments without suspending service. We propose three mobile computing services: user virtual environment (UVE), mobile virtual terminal (MVT), and virtual resource management (VRM). UVE provides users with a uniform view of their working environments independent of current locations and specific terminals. MVT extends traditional terminal mobility by preserving the terminal execution state for restoration at new locations, including active processes and subscribed services. VRM permits mobile users and terminals to maintain access to resources and services by automatically requalifying the bindings and moving specific resources or services to permit load balancing and replication     

��DDS: A Middleware for Real-time Wireless Embedded Systems

A Real-Time Wireless Distributed Embedded System (RTWDES) is formed by a large quantity of small devices with certain computing power, wireless communication and sensing/actuators capabilities. These types of networks have become popular as they have been developed for applications which can carry out a vast quantity of tasks, including home and building monitoring, object tracking, precision agriculture, military applications, disaster recovery, industry applications, among others. For this type of applications a middleware is used in software systems to bridge the gap between the application and the underlying operating system and networks. As a result, a middleware system can facilitate the development of applications and is designed to provide common services to the applications. The development of a middleware for sensor networks presents several challenges due to the limited computational resources and energy of the different nodes. This work is related with the design, implementation and test of a micro middleware for RTWDES; the proposal incorporates characteristics of a message oriented middleware thus allowing the applications to communicate by employing the publish/subscribe model. Experimental evaluation shows that the proposed middleware provides a stable and timely service to support different Quality of Service (QoS) levels.     

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.     

Programmable mobile networks

Existing mobile systems (e.g., mobile IP, mobile ATM and third generation cellular systems) lack the intrinsic architectural flexibility to deal with the complexity of supporting adaptive mobile applications in wireless and mobile environments. We believe that there is a need to develop alternative network architectures from the existing ones to deal with the demands placed on underlying mobile signalling, adaptation management and wireless transport systems in support of new mobile services, e.g. interactive multimedia and web access. In this paper we present the design, implementation and evaluation of mobiware, a middleware technology that enables the introduction of new services in mobile networks. Mobiware provides a toolkit that service providers can utilize to build services that can dynamically exploit the intrinsic scalable properties of mobile multimedia applications in response to time-varying mobile network conditions. Based on an open programmable networking paradigm, mobiware runs on mobile devices, wireless access points and mobile-capable switch/routers providing a set of open programmable interfaces and distributed objects for adaptive mobile networking. Mobiware is software-intensive and is built on CORBA and Java distributed object technologies. The source code for mobiware v1.0 is freely available (comet.columbia.edu/mobiware) for experimentation.     

An overview of the Real-Time CORBA specification

A growing class of real-time systems require end-to-end support for various quality-of-service (QoS) aspects, including bandwidth, latency, jitter and dependability. Applications include command and control, manufacturing process control, videoconferencing, large-scale distributed interactive simulation, and testbeam data acquisition. These systems require support for stringent QoS requirements. To meet this challenge, developers are turning to distributed object computing middleware, such as the Common Object Request Broker Architecture, an Object Management Group (OMG) industry standard. In complex real-time systems, DOC middleware resides between applications and the underlying operating systems, protocol stacks and hardware. CORBA helps decrease the cycle time and effort required to develop high-quality systems by composing applications using reusable software component services rather than building them entirely from scratch. The Real-Time CORBA specification includes features to manage CPU, network and memory resources. The authors describe the key Real-Time CORBA features that they feel are the most relevant to researchers and developers of distributed real-time and embedded systems     

Design and implementation of a smart system for personalization and accurate selection of mobile services

Wireless mobile services are computing applications that run on handheld wireless devices. Such applications must work within the daunting constraints of the devices, which include memory, processing power, input capabilities, and size of display. It is therefore important that mobile services take into account the user’s context, optimize resource usage, and minimize input effort imposed on the user. In this paper, we present the design and implementation of a smart agent-enabled system for personalizing wireless mobile services and advertisements for Java 2 Micro Edition (J2ME) or Java ME, and Wireless Application Protocol (WAP) enabled devices. We use software agents for context filtering because such autonomous software entities have characteristics that can benefit mobile devices and the wireless environment, and the Composite Capability/Preference Profiles (CC/PP) standard for defining profiles for user preferences and device capabilities. The system incorporates the use of artificial neural networks to adaptively and iteratively learn to select the best available service based on contextual information. The system is evaluated using practical operating scenarios, as well as empirical data and results show an 87% success rate in the selection of the best available service.     

Intelligent service processing in common USN middleware

The Ubiquitous sensor network (USN) is composed of several heterogeneous sensors with a variety of characteristics. An application based on the sensor network also has various requirements to provide services to users. Therefore it is important to develop the common USN middleware for flexible integration between the sensor networks and applications. Especially, this paper focuses on intelligent service management which is one of the main functions of USN middleware. Several applications in the sensor network environment support not only monitoring services, but also sensor-based context-awareness and intelligent services. In many applications, however, approaches to support intelligent services depend on the application because the standard method has been undefined yet. Therefore this paper proposes a common method for processing intelligent services in USN middleware independent of an application. The proposed method is implemented and evaluated as a component of USN middleware.     

Reconfigurable Service Composition and Categorization for Power-Aware Mobile Computing

The requirement of agile adaptation to varying resource constraints in mobile systems motivates the use of a service-oriented architecture (SOA), which can support the composition of two or more services to form a complex service. In this paper, we propose SOA-based middleware to support QoS control of mobile applications and to configure an energy-efficient service composition graph. We categorize services into two layers:functionality-centric services, which are connected to create a complex service to meet the user's intentions, and resource-centric services, which undertake distributed functionality-centric services in a way that increases the success rate of service composition while reducing contention at specific service nodes. We also present a service routing algorithm to balance the resource consumption of service providers on a service-overlay network. Through simulation of power-aware service composition using a realistic model based on ns-2 and traced data, we demonstrate that our approach can help both the mobile devices and the servers in a service-overlay network to reduce energy consumption without an increase in response time.     

中间件技术在自来水营收系统中的应用

中间件是一种独立的系统软件或服务程序,分布式应用系统借助这种软件在不同的技术之间共享资源,管理计算资源和网络通讯。在应用系统中采用合适的中间件能够降低应用系统的复杂度,缩短开发周期。本文针对营收业务和银行联网收费的需求特点,分析中间件技术的应用,研究DataSnap应用服务器中间件和WebSphereMQ消息队列中间件...     

Wireless network extension using mobile IP

Over the last two decades, we have seen a dramatic shift in computing systems, away from the monolithic mainframe and toward increasingly distributed, client-server systems. One of the key elements enabling the success of the distributed computing environment was the interconnecting network technology. High-speed, reliable network hardware and protocols evolved to support client-server applications. Network technology has now progressed to the point that applications are being written to specifically exploit the capabilities of the network. The explosion of World Wide Web applications is the latest example of the fact that the network is now the focus of the distributed computing environment. In a concurrent development, personal computing platforms placed increasingly powerful systems in ever smaller form factors. Users have embraced these advances: Mobile computers, in the form of laptops, palmtops, and personal digital assistants (PDAs), are a significant element of the current computing environment. However, to be fully productive, the mobile computer user requires access to the network. Further, access to a network is not sufficient. Mobile users need access to the same network-the same resources and services and communications capabilities-that they would if they were at their desktops. We refer to this concept of providing home network access to the mobile user as network extension. Addressing many requirements for practical wireless access, this Internet technology aids the development of advanced data services for wireless networks, including the integrated dispatch enhanced network     

Scalable networked information processing environment (SNIPE)

Scalable Networked Information Processing Environment (SNIPE) is a metacomputing system that aims to provide a reliable, secure, fault-tolerant environment for long-term distributed computing applications and data stores across the global Internet. This system combines global naming and replication of both processing and data to support large-scale information processing applications leading to better availability and reliability than currently available with typical cluster computing and/or distributed computer environments. To facilitate this the system supports: distributed data collection, distributed computation, distributed control and resource management, distributed output and process migration. The underlying system supports multiple communication paths, media and routing methods to aid performance and robustness across both local and global networks. This paper details the goals, design and an initial implementation of SNIPE, and then demonstrates its usefulness in supporting a middleware project. Initial communications performance is also presented.     

支持移动计算的反射式中间件

传统中间件基于黑盒的设计思想,缺乏必要的灵活性,无法适应复杂动态多变的移动计算环境。反射技术可以使应用程序在运行时检查中间件所提供的服务类型,动态的构造调用请求,适应变化的环境。文章研究了反射的相关概念,中间件技术,分析了移动计算的实际需求,提出了一个支持移动计算的反射中间件架构,支持环境感知、异步通信、动态重配置等。     

Generic support for distributed applications

In the late 1980s, software designers introduced middleware platforms to support distributed computing systems. Since then, the rapid evolution of technology has caused an explosion of distributed-processing requirements. Application developers now routinely expect to support multimedia systems and mobile users and computers. Timely response to asynchronous events is crucial to such applications, but current platforms do not adequately meet this need. Another need of existing and emerging applications is the secure interoperability of independent services in large-scale, widely distributed systems. Information systems serving organizations such as universities, hospitals, and government agencies require cross-domain interaction. To meet the needs of these applications, Cambridge University researchers developed middleware extensions that provide a flexible, scalable approach to distributed-application development. This article details the extensions they developed, explaining their distributed software approach and the support it has provided for emerging applications     

移动云环境中基于节点自适应配置的可靠服务架构

为了解决移动云计算系统中因链接断开和网络分区对服务可靠性的影响问题,提出一种基于服务副本管理和节点自适应配置的服务软件架构。其由通信中间件、监测系统、上下文管理器以及副本管理器组成。根据监测到的服务需求和节点信息,副本管理器通过一种自适应配置算法来激活或休眠节点,使任务能够在当前最适合的节点中执行,以此提高计算服务系统的可靠性。案例结果表明,该方案能够保证动态网络环境中的服务可靠性。