Supporting Service Discovery,Querying and Interaction in Ubiquitous Computing Environments

In this paper, we contend that ubiquitous computing environments will be highly heterogeneous, service rich domains. Moreover, future applications will consequently be required to interact with multiple, specialised service location and interaction protocols simultaneously. We argue that existing service discovery techniques do not provide sufficient support to address the challenges of building applications targeted to these emerging environments.This paper makes a number of contributions. Firstly, using a set of short ubiquitous computing scenarios we identify several key limitations of existing service discovery approaches that reduce their ability to support ubiquitous computing applications. Secondly, we present a detailed analysis of requirements for providing effective support in this domain. Thirdly, we provide the design of a simple extensible meta-service discovery architecture that uses database techniques to unify service discovery protocols and addresses several of our key requirements. Lastly, we examine the lessons learnt through the development of a prototype implementation of our architecture.     

A Semantic Service Discovery Network for Large‐Scale Ubiquitous Computing Environments

This paper presents an efficient semantic service discovery scheme called UbiSearch for a large‐scale ubiquitous computing environment. A semantic service discovery network in the semantic vector space is proposed where services that are semantically close to each other are mapped to nearby positions so that the similar services are registered in a cluster of resolvers. Using this mapping technique, the search space for a query is efficiently confined within a minimized cluster region while maintaining high accuracy in comparison to the centralized scheme. The proposed semantic service discovery network provides a number of novel features to evenly distribute service indexes to the resolvers and reduce the number of resolvers to visit. Our simulation study shows that UbiSearch provides good semantic searchability as compared to the centralized indexing system. At the same time, it supports scalable semantic queries with low communication overhead, balanced load distribution among resolvers for service registration and query processing, and personalized semantic matching.     

异构个人域网络中的服务发现机制

个人周边智能设备与移动业务的融合促进了服务发现机制的发展,智能设备的增加和移动性也使得现有服务发现机制很难在用户移动当中始终提供有效服务。在对个人周边的异构网络特征分析的基础上,利用组播和信息熔合等技术,提供了一套适用于节点具有群组移动性、异构性的动态网络的可靠的服务发现机制,并且不会消耗过多的系统带宽资源。     

通用即插即用服务自动发现技术

随着数字家电的普及，家庭网络技术呈现出越来越广阔的市场应用前景。为了实现家庭网络互联设备的操作控制和信息共享，需要采用通用即插即用（UPnP）技术。UPnP充分重用包括IP、传输控制协议（TCP）、数据报协议（UDP）、超文本传输协议（HTTP）和可扩展标记语言（XML）在内的互联网技术标准，提供服务的跨平台自动发现和远程控制。采用UPnP可实现灵活而强大的业务发现能力，能将复杂的网络设备驱动变为简单的远程网络控制，同时还能提供互联设备的操作控制和信息共享。     

Centaurus: An Infrastructure for Service Management in Ubiquitous Computing Environments

In the near future, we will see dramatic changes in computing and networking hardware. A large number of devices (e.g., phones, PDAs, even small household appliances) will become computationally enabled. Micro/nano sensors will be widely embedded in most engineered artifacts, from the clothes we wear to the roads we drive on. All of these devices will be (wirelessly) networked using Bluetooth, IEEE 802.15 or IEEE 802.11 for short range connectivity creating pervasive environments. In this age where a large number of wirelessly networked appliances and devices are becoming commonplace, there is a necessity for providing a standard interface to them that is easily accessible by any user. This paper outlines the design of Centaurus, an infrastructure for presenting services to heterogeneous mobile clients in a physical space via some short range wireless links. The infrastructure is communication medium independent; we have implemented the system over Bluetooth, CDPD and Infrared, three well-known wireless technologies. All the components in our model use a language based on Extensible Markup Language (XML) for communication, giving the system a uniform and easily adaptable interface. Centaurus defines a uniform infrastructure for heterogeneous services, both hardware and software, to be made available to diverse mobile users within a confined space.     

A Method for Resource and Service Discovery in MANETs

The paper presents a novel resource and service discovery mechanism for MANETs using Routing Intelligent Mobile Agents(RIMAs). RIMAs periodically collect routing, resource and service availability information and index the same in appropriate RIMA nodes. Every mobile node is close to atleast one RIMA node. The mobile node running an application in need of a resource or a service dispatches a Discovery agent to its nearest RIMA node. The index available at the RIMA node will guide the Discoverer agent to the resource or service node. Analysis of the method reveals the computational complexity to be of the order of square of number of RIMA nodes. Communication overheads are the product of number of generated agents, agent size and number of hops travelled by an agent. The method has been simulated and tested on MANETs of varying sizes from 50 to 800 nodes. Simulation snapshots and results show the proper working and success of the algorithm. Basavaraj Talwar is a Research Assistant at the Protocol Engineering & Technology Unit in Electrical Communication and Engineering department in Indian Institute of Science, Bangalore, India. He is research interests include Applications of mobile agents in MANETs and mobile commerce security. Prof. Pallapa Venkataram is the Chief Programming Executive of Protocol Engineering & Technology Unit, Electrical Communication and Engineering department in Indian Institute of Science, Bangalore, India. He has over 160 publications at various levels. His research interests include Protocol Engineering, Mobile Agents, Mobile Commerce, Wireless Networks, Mobile Computing, Artificial Intelligence. He is a senior member of IEEE and has received numerous awards and other fellowships for his contributions. Prof. Lalit M. Patnaik is currently associated with Computer Science and Automation department in Indian Institute of Science, Bangalore, India. He has currently over 400 publications at various levels. His research interests include Computer Architecture, Parallel & Distributed Computing, CAD of VLSI Systems, Real-Time Systems, Soft Computing, Engineering Applications of Information Technology, Mobile Computing, Computational Neuroscience. He is a fellow of IEEE and has received numerous awards and other fellowships for his contributions.     

A Secure Infrastructure for Service Discovery and Access in Pervasive Computing

Security is paramount to the success of pervasive computing environments. The system presented in this paper provides a communications and security infrastructure that goes far in advancing the goal of anywhere-anytime computing. Our work securely enables clients to access and utilize services in heterogeneous networks. We provide a service registration and discovery mechanism implemented through a hierarchy of service management. The system is built upon a simplified Public Key Infrastructure that provides for authentication, non-repudiation, anti-playback, and access control. Smartcards are used as secure containers for digital certificates. The system is implemented in Java and we use Extensible Markup Language as the sole medium for communications and data exchange. Currently, we are solely dependent on a base set of access rights for our distributed trust model however, we are expanding the model to include the delegation of rights based upon a predefined policy. In our proposed expansion, instead of exclusively relying on predefined access rights, we have developed a flexible representation of trust information, in Prolog, that can model permissions, obligations, entitlements, and prohibitions. In this paper, we present the implementation of our system and describe the modifications to the design that are required to further enhance distributed trust. Our implementation is applicable to any distributed service infrastructure, whether the infrastructure is wired, mobile, or ad hoc.     

一种基于本体语义的网格服务发现模型

在网格环境中,网格服务的发现机制对于系统的性能和效率有着重要的意义和作用。目前网格服务发现模型多数是集中式的、基于关键字的服务匹配模型,缺乏灵活性和推理能力,发现结果难以令人满意。提出了一种基于本体论语义和Agent代理的网格服务发现模型。采用Agent代理技术进行服务搜索,不同的代理能够提供不同领域的本体知识库,从而达到多领域的服务发现;利用本体论语义进行服务的匹配,从而达到智能化的服务发现。该模型提高了服务发现的准确率,同时也增强了系统的可维护性、灵活性和扩展性以及服务管理的自治性和容错性。     

蓝牙服务搜索协议的实现

为简洁高效地实现蓝牙服务搜索协议,给出了它的实现方法,包括数据元报头的位模实现,服务记录表的构建以及搜索过程的方法。实验结果表明,这些方法不但可以与商用手机实现互相搜索的功能,而且简单,可靠性强,具有较高的应用价值。     

Service Composition for Mobile Environments

Service Composition, that is, the development of customized services by discovering, integrating and executing existing services has received a lot of attention in the last couple of years with respect to wired-infrastructure or Internet web services. With the advancement in the wireless technology and rapid deployment of mobile devices, we envision that in the near future wirelessly connected mobile devices in a given vicinity will also provide services that can be leveraged in the composition process. This is particularly true of what have been described as “pervasive computing” environments. However, wired-infrastructure based service composition architectures are not designed to consider the various factors like mobility, device heterogeneity, resource variability and reliability in a mobile environment. In this paper, we describe the issues related to service composition in mobile environments and evaluate criteria for judging protocols that enable such composition. We present a distributed architecture and associated protocols for service composition in mobile environments that take into consideration mobility, dynamic changing service topology and device resources. The composition protocols are based on distributed brokerage mechanisms and utilize a distributed service discovery process over ad-hoc network connectivity. We present simulation results of our protocols, and compare them with a centralized service composition protocol traditionally used for wired-infrastructure environments. The results show that our approach clearly outperforms the existing centralized approaches, and that our protocols are able to adapt and better utilize the changing service topology and resources in a mobile environment.This work is supported in part by NSF awards 9875433 and 0070802, DARPA DAML program and IBM. Dipanjan Chakraborty is a Ph.D candidate and a research member of ebiquity research group at University of Maryland, Baltimore County (UMBC). His reserach is in the areas of mobile and pervasive computing environments, mobile and e-commerce, peer-to-peer systems with special interests in the fields of service discovery, information aggregation and composition, ad-hoc network application-centric routing, agent-based systems. He specializes in the development and modeling of distributed architectures to enable mobile and pervasive commerce in ubiquitous environments. His thesis is in the area of service discovery and composition for pervasive environments. He has been a fellow of IBM during the 3 years of his Ph.D candidacy. Anupam Joshi is an Associate Professor of Computer Science and Electrical Engineering at UMBC. Earlier, he was an Assistant Professor in the CECS department at the University of Missouri, Columbia. He obtained a B. Tech degree in Electrical Engineering from IIT Delhi in 1989, and a Masters and Ph.D. in Computer Science from Purdue University in 1991 and 1993 respectively. His research interests are in the broad area of networked computing and intelligent systems. His primary focus has been on data management for mobile computing systems in general, and most recently on data management and security in pervasive computing and sensor environments. He has created agent based middleware to support discovery, composition, and secure access of services/data over both infrastructure based (e.g. 802.11, cellular) and ad-hoc wireless networks (e.g. Bluetooth). He is also interested in Semantic Web and Data/Web Mining, where he has worked on personalizing the web space using a combination of agents and soft computing. His other interests include networked HPCC. He has published over 50 technical papers, and has obtained research support from NSF, NASA, DARPA, DoD, IBM, AetherSystens, HP, AT&T and Intel. He has presented tutorials in conferences, served as guest editor for special issues for IEEE Personal Comm., Comm. ACM etc., and served as an Associate Editor of IEEE Transactions of Fuzzy Systems from 99-03. At UMBC, Joshi teaches courses in Operating Systems, Mobile Computing, Networking, and Web Mining. He is a member of IEEE, IEEE-CS, and ACM. Tim Finin is a Professor in the Department of Computer Science and Electrical Engineering at the University of Maryland Baltimore County (UMBC). He has over 30 years of experience in the applications of Artificial Intelligence to problems in information systems, intelligent interfaces and robotics and is currently working on the theory and applications of intelligent software agents, the semantic web, and mobile computing. He holds degrees from MIT and the University of Illinois. Prior to joining the UMBC, he held positions at Unisys, the University of Pennsylvania, and the MIT AI Laboratory. Finin is the author of over 180 refereed publications and has received research grants and contracts from a variety of sources. He has been the past program chair or general chair of several major conferences. He is a former AAAI councilor and is a member of the the board of directors of the Computing Research Association. Yelena Yesha received the B.Sc. degree in Computer Science from York University, Toronto, Canada in 1984, and the M.Sc. and Ph.D degrees in Computer and Information Science from The Ohio State University in 1986 and 1989, respectively. Since 1989 she has been with the Department of Computer Science and Electrical Engineering at the University of Maryland Baltimore County, where she is presently a Verizon Professor. In addition, from December, 1994 through August, 1999 Dr. Yesha served as the Director of the Center of Excellence in Space Data and Information Sciences at NASA. Her research interests are in the areas of distributed databases, distributed systems, mobile computing, digital libraries, electronic commerce, and trusted information systems. She published 8 books and over 100 refereed articles in these areas. Dr. Yesha was a program chair and general co-chair of the ACM International Conference on Information and Knowledge Management and a member of the program committees of many prestigious conferences. She is a member of the editorial board of the Very Large Databases Journal, and the IEEE Transaction on Knowledge and Data Engineering, and is editor-in-chief of the International Journal of Digital Libraries. During 1994, Dr. Yesha was the Director of the Center for Applied Information Technology at the National Institute of Standards and Technology. Dr. Yesha is a senior member of IEEE, and a member of the ACM.This revised version was published online in August 2005 with a corrected cover date.     

Piecewise Network Awareness Service for Wireless/Mobile Pervasive Computing

This paper presents a piecewise framework for network awareness service (NAS) for wireless/mobile pervasive computing. We investigate how piecewise consideration of wired and wireless elements of the framework architecture benefits service advertisement and discovery and network-awareness techniques. We also discuss scalability of the NAS framework with respect to platform computing capabilities. The framework is suitable for a wide range of computing devices, from powerful ones with multi-tasking operating systems (OS) to small ones with lightweight OS. Case studies applying the NAS framework to sensor monitoring in home networks and data streaming in pervasive multimedia computing are presented. The analytical results on the performance of the NAS framework in these case studies show that it has significant advantages over traditional network-awareness frameworks in terms of reducing wireless bandwidth consumption and saving battery energy of mobile devices.     

MARE: Resource Discovery and Configuration in Ad Hoc Networks

The emergence of personal portable devices, such as PDA's and Mobile phones, with considerable processing and communication capabilities, has led to a desire to use various combinations of these devices together to achieve new and as yet unrealised operations. Not only are mobile devices expected to offer conventional facilities like email and web browsing but also more demanding multimedia applications. Attaining these operations within a fixed network environment with high-power workstations is non-trivial; however, highly dynamic ad hoc environments further complicate this scenario. In particular, a means of discovering available devices and enabling manipulation of them within a highly active environment is required. In this paper we present a novel architecture called MARE that facilitates the detection and manipulation of resources in ad hoc environments.     

面向移动云计算的自适应服务选择方法研究

Despite the rapid advances in mobile tech-nology, many constraints still prevent mobile de-vices from running resource-demanding applica-tions in mobile environments. Cloud computing with flexibility, stability and scalability enables ac-cess to unlimited resources for mobile devices, so more studies have focused on cloud computing- based mobile services. Due to the stability of wire-less networks, changes of Quality of Service (QoS) level and user' real-time preferences, it is becoming challenging to determine how to adaptively choose the “appropriate”service in mobile cloud compu-ting environments. In this paper, we present an a-daptive service selection method. This method first extracts user preferences from a service's evaluation and calculates the similarity of the service with the weighted Euclidean distance. Then, they are com-bined with user context data and the most suitable service is recommended to the user. In addition, we apply the fuzzy cognitive maps-based model to the adaptive policy, which improves the efficiency and performance of the algorithm. Finally, the experi-ment and simulation demonstrate that our approach is effective.     

基于Agent的内网安全系统研究

针对目前分散式安全服务的种种弊端,通过将多Agent系统的多种特性引入网络安全系统,提出了一种基于网络拓扑结构感应能力以及行为自主性的多Agent融合方法的网络安全系统模型.以身份认证、访问控制、漏洞检测、安全审计等网络安全业务设计和实现了多种类型Agent,使网络安全系统提高了适应性能力等特征.通过自保护检测服务,确保Agent的安全通信及平台的顺利实施.该系统能有效地实施上述安全任务,提高网络安全;并能充分利用现有设备,实施廉价,可扩展性好.     

A Comprehensive Service Discovery Solution for Mobile Ad Hoc Networks

Service discovery is an integral part of constructing self-configuring Mobile Ad Hoc Networks (MANETs). While several service discovery protocols have been developed, most of them are designed for infrastructure-based networks and thus not suitable to be used in MANETs. Due the volatile nature of MANET, service discovery protocols designed for MANETs often suffer from problems. Firstly, they have limited scalability due to the extensive use of broadcast communication. Secondly, they usually lack context-aware selection mechanisms and feature only reduced interaction standards. This paper proposes a network layer supported comprehensive service discovery solution that addresses the above issues and provides a solution in two parts. First it discusses a location-aware network layer routing protocol that groups mobile nodes into clusters while a gateway in each cluster is responsible for routing. Secondly, this paper proposes a service discovery protocol that utilizes directories for service discovery that interact with lower network layer gateway configurations. In this architecture, gateways are also used as directories for service discovery to improve performance. In doing so, we improve the system’s overall efficiency by eliminating the use of complex graph-based algorithms for maintaining clusters and establishing virtual backbones. Furthermore, this service discovery solution includes an agent-based context-aware service selection, and provides standard mechanisms for different types of service interaction. Jerry Tyan is a graduate student in the Department of Computing and Information Science at the University of Guelph in Guelph, Canada. Jerry holds a B.Sc. in Computer Science from Simon Fraser University in Vancouver, Canada. His research interests are in the area of service discovery protocols for mobile ad hoc networks. Qusay H. Mahmoud is an Assistant Professor in the Department of Computing and Information Science at the University of Guelph, and Associate Chair of the Distributed Computing and Wireless & Telecommunications Systems Technology program at the University of Guelph-Humber in Toronto, Canada. He received a B.Sc. in Data Analysis and an M.Sc. in Computer Science, both from the University of New Brunswick (Canada), and a Ph.D. in Computer Science from Middlesex University (UK). Dr. Mahmoud has published dozens of research papers and two books. Also, he has organized several research events, edited their proceedings, and presented tutorials at several international conferences worldwide. His research interests include wireless computing, agent technology, service discovery protocols, and Web-based systems. He is a member of the ACM and the IEEE Computer Society.This revised version was published online in August 2005 with a corrected cover date.     

Pervasive data access in wireless and mobile computing environments

The rapid advance of wireless and portable computing technology has brought a lot of research interests and momentum to the area of mobile computing. One of the research focus is on pervasive data access. With wireless connections, users can access information at any place at any time. However, various constraints such as limited client capability, limited bandwidth, weak connectivity, and client mobility impose many challenging technical issues. In the past years, tremendous research efforts have been put forth to address the issues related to pervasive data access. A number of interesting research results were reported in the literature. This survey paper reviews important works in two important dimensions of pervasive data access: data broadcast and client caching. In addition, data access techniques aiming at various application requirements (such as time, location, semantics and reliability) are covered. Copyright © 2006 John Wiley & Sons, Ltd.     

Service Discovery in Ad Hoc Networks: Performance Evaluation and QoS Enhancement

With the increasing popularity of wireless portable devices, such as laptops, PDAs and mobile phones, it is getting more and more important for mobile users to discover their required resources (e.g. printers and fax machines) without any need of configurations. To this end, automatic service discovery is an important feature of mobile Ad Hoc networks (Manets). In this paper a service discovery protocol for Manets based on the IETF Service Location Protocol has been implemented in the NS-2 simulator. Its performance is studied under different mobility patterns, network sizes and number of service agents. A lightweight quality of service (QoS) aware service discovery protocol is also proposed to support QoS applications. Zhong Fan is currently a Principal Researcher with Toshiba Research Europe in Bristol, UK. He received the B.S. and M.S. degrees in Electronic Engineering from Tsinghua University, China and the Ph.D. degree in Telecommunication Networks from Durham University, UK. His research interests are protocol design and performance analysis of wireless networks.