Path and Oracle Discovery Protocol for Centralized Bandwidth Reservation Mechanisms

The introduction of Differential Service architecture has initiated interests in centralized bandwidth reservation via an oracle with each network domain defining its own oracle. The centralized bandwidth reservation mechanism requires knowledge of network topology and reservation paths in the domain to control access to premium services as well as log usage. We propose a new reactive protocol, Path and Oracle Discovery Protocol (PODP), to facilitate the management of networks with centralized bandwidth reservations. This protocol discovers the routers traversed by the network connection request and the respective domain oracle. PODP is able to respond to network path changes at minimum network overhead and storage requirements compared to other methods. A prototype router and oracle supporting the PODP has been successfully developed and tested across multiple domains.     

Internet Telephony: architecture and protocols – an IETF perspective

Internet telephony offers the opportunity to design a global multimedia communications system that may eventually replace the existing telephony infrastructure. We describe the upper-layer protocol components that are specific to Internet telephony services: the Real-Time Transport Protocol (RTP) to carry voice and video data, and the Session Initiation Protocol (SIP) for signaling. We also mention some complementary protocols, including the Real Time Streaming Protocol (RTSP) for control of streaming media, and the Wide Area Service Discovery Protocol (WASRV) for location of telephony gateways.     

Context-aware pervasive service composition and its implementation

Incorporating service composition and pervasive computing into managing users’ complex everyday activities calls for the Pervasive Service Composition paradigm for everyday life. In this paper, we propose the concept of Context-Aware Pervasive Service Composition (CAPSC), which aims at enabling a pervasive system to provide user service compositions that are relevant to the situation at hand. We investigate CAPSC requirements and design a CAPSC architecture by taking into account context-aware peer coordination, context-aware process service adaptation, and context-aware utility service adaptation. We present a proof of concept application prototype as well.     

一种广域移动服务定位技术

IETF建议的服务定位协议(Servi Location Protocol…SLP)使得计算机很少需要(甚至不需要)静态地配置就可以自动发现并方便地使用所需的网络服务。然而，SLP并不适用于在广域网范围内进行服务的定位以及选择，而且不能够有效地支持移动计算特别是服务移动情况下的服务定位与选择。因此，本文提出了一种广域移动服务定位技术，它通过层次结构的目录代理(Directozy Agent…DA)有效增强了SLP在广域网中的可扩展性，并在设计时充分考虑了移动服务问题，为SLP提供了对移动计算的支持。这种技术具有良好的可扩展性，容错性以及移动支持功能。     

一种改进的位置信息服务方法

在许多情况下,移动主机需要获得网络中其他移动主机精确或概略的位置信息,即需要一种位置服务。在对目前现有的 5种位置服务即位置信息洪泛、DREAM位置服务、简单位置服务、反应式位置服务和GLS位置服务进行简单描述和性能比较的基础上,提出了一种新的位置服务,简单新位置更新服务(SNLUS)。它通过在位置信息表中增加“信息更新标识”对目前较好的简单位置服务协议(SLS)进行了改进。仿真结果说明,该算法可以用较少的开销获得较好的位置信息服务。     

Performance evaluation of an efficient fault tolerant service discovery protocol for vehicular networks

Recently, vehicular networks and inter-vehicle communication have received attention from the research community and the automotive industry. In this context, many services are deployed in vehicular networks that are beneficial to drivers and passengers. Service discovery in vehicular networks is vital to make such services useful. However, due to the lack of communication reliability in vehicular ad hoc networks, it is necessary to implement fault-tolerant techniques during the discovery of service providers in vehicular networks. Very few service discovery protocols for vehicular networks have considered fault tolerant techniques, which are very important for the efficiency of service discovery. Fault tolerant techniques improve service request satisfaction and reduce dropped connections due to faulty components between the service provider and the service requester. In this paper, we propose a fault tolerant location based service discovery protocol for vehicular networks which can work well under service provider failures, communication link failures and roadside router failures. Our protocol permits the discovery of location based services where the requester specifies the region of interest within the request. Our protocol uses an infrastructure support consisting of clusters of roadside routers formed in specific regions in the vehicular network. In addition, service discovery messages are integrated into the network layer and use channel diversity in order to improve service discovery efficiency. We describe our fault tolerant location based vehicular service discovery protocol (FTLocVSDP) and discuss its proof of correctness and performance evaluation. We prove that the success rate is improved in the roadside router failure and in the communication link failure scenarios by 50% and 30%, respectively, compared to the location based service discovery protocol for vehicular networks (LocVSDP) which does not consider fault tolerant techniques.     

WSB: a broker‐centric framework for quality‐driven web service discovery

Web service interfaces can be discovered through several means, including service registries, search engines, service portals, and peer‐to‐peer networks. But discovering Web services in such heterogeneous environments is becoming a challenging task and raises several concerns, such as performance, reliability, and robustness. In this paper, we introduce the Web Service Broker (WSB) framework that provides a universal access point for discovering Web services. WSB uses a crawler to collect the plurality of Web services disseminated throughout the Web, continuously monitor the behavior of Web services in delivering the expected functionality, and enable clients to articulate service queries tailored to their needs. The framework features ranking algorithms we have developed which are capable of ranking services according to Quality of Web Service parameters. WSB can be seamlessly integrated into the existing service‐oriented architectures. Copyright © 2010 John Wiley & Sons, Ltd.     

CircleSearch：流媒体VoD环境下的P2P搜索算法

在基于P2P的流媒体VoD环境下,搜索机制是影响服务质量的关键因素之一。该文提出一种新的基于环状网络的分布式自适应概率搜索算法——CircleSearch。它依据节点本体内容生成结构化的环状拓扑网络,保证算法的可扩展性、健壮性和分布性。自发组织基于本体距离和连接可靠性的small world覆盖网络,减小消息的转发次数,采用自适应搜索算法提高文件定位的准确性。仿真实验表明,CircleSearch以其高成功率、低服务器负载和很小的平均搜索长度实现媒体流传输的即时、稳定、可控和连续,为VoD服务提供QoS保证。     

Service level agreements for DiffServ-based services' provisioning

The evolution of mechanisms for providing Quality-of-Service (QoS) over the contemporary network infrastructures has introduced the need for regulation and management of the emerging QoS services with the use of Service Level Agreements (SLAs). SLAs define the qualitative and quantitative characteristics of the services provided from a network provider to peering networks or customers. In this work, we define a template for the SLA structure to support the provision of a QoS service between two peering domains and then we proceed with the definition of an end-to-end SLA across consecutive domains, based on the bilateral ones. We also propose a model for the service provisioning procedures.     

Toward secure and private service discovery anywhere anytime

With the advances in and convergence of Internet technologies, embedded computers, and wireless communication, computing devices have become part of our daily life. Hand-held devices and sensors with wireless connections create opportunities for many new nomadic applications. Service discovery is an essential component for cognitive science to discover existing network services just-in-time. Unlike many other approaches, we propose a service discovery model supporting nomadic users and services in public environments. Our model emphasizes secure and private service discovery in such environments. Location sensing is integrated for location dependent service discovery and is used to lessen service discovery network infrastructure requirements. We analyze the system performance and show our formal verification of the protocols. Our implementation shows that our model is feasible.     

Toward secure and private service discovery anywhere anytime

With the advances in and convergence of Internet technologies, embedded computers, and wireless communication, computing devices have become part of our daily life. Hand-held devices and sensors with wireless connections create opportunities for many new nomadic applications. Service discovery is an essential component for cognitive science to discover existing network services just-in-time. Unlike many other approaches, we propose a service discovery model supporting nomadic users and services in public environments. Our model emphasizes secure and private service discovery in such environments. Location sensing is integrated for location dependent service discovery and is used to lessen service discovery network infrastructure requirements. We analyze the system performance and show our formal verification of the protocols. Our implementation shows that our model is feasible.     

基于语义描述的分布式Web服务发布与发现

结合P2P与Web服务语义描述技术，提出了一种基于分布式哈希表的非集中式Web服务发布与发现方法。通过定义服务供求双方共同遵守的领域本体，实现具有同样语义概念的两种不同描述的统一，提高服务发现的效率和准确度。利用类别本体对领域本体的组织，提出了层次式Web服务目录系统。基于该系统，服务的发布与发现是在特定应用领域范围内进行，因此减少了服务搜索空间，提高了服务发现的效率。     

RTSP流媒体代理IPv4/IPv6组播互通的研究

基于RTSP协议的流媒体应用发展迅速,在Internet上传输流媒体的相关技术成为热点。在网络和网络应用从IPv4向IPv6过渡的过程中,新构建的基于IPv6的实时RTSP流媒体组播应用要求能够与原有基于IPv4的实时RTSP流媒体组播应用互通。分析了当前主流的流式多媒体信息的发布平台Microsoft的Windows MediaService以及RealNetworks的Helix Universal Server对组播的实现方式,并研究对支持IPv4/IPv6网络间互访的RTSP流媒体应用代理进行一些扩展来实现IPv4/IPv6 RTSP流媒体组播应用互通。     

一种新的适用于车载Ad-hoc网络的位置服务机制

提出了一种新的适用于车载Ad-hoc网络的位置服务机制ILSV(道路交叉路口位置服务),该机制充分利用了车载网络环境的特点如存在十字路口,受交通规则约束等,将网络中节点的位置信息分布地存储在位于十字路口的位置服务器上。在大规模城市仿真场景下的仿真结果表明:通过与GLS和HLS相比,ILSV获得了相当高的查询成功率,并且在网络半径很大的情况下具有较优的可缩放性。     

Integration of transient Web services into a virtual peer to peer Web service registry

Transient Web service provisioning implies a variety of different requirements that are hard to meet in traditional Web service environments. Currently, Web service brokerage focuses on centralized or replicated architectures. We argue that such systems are not efficient when it comes to dynamic, respectively ad hoc, Web service provisioning. We propose a distributed peer to peer Web service registry solution based on lightweight Web service profiles. We further introduce the notion of views that allow the specification of arbitrary contexts of Web services and provide a working example to illustrate our approach. Finally, we present a prototype that uses tuple spaces as global storage and communication means.     

基于增强现实技术的移动LBS系统的设计与实现

基于位置服务发展迅速。利用增强现实技术开发LBS系统．对人机界面与GIS服务整合具有重要的理论和现实意义。在此基础上,设计一个空间信息服务的构建与发布机制．利用智能终端配备的传感装置,在Android平台手持设备下扩展增强现实功能．融合真实场景和虚拟信息,搭建远程Web服务器完成数据交互,得到整体基于Web服务的LBS原型系统。     

Standortplanung für Anbieter von IT-Services

Location Planning for IT Service Vendors On global markets location planning plays an important role in the strategies of IT-service vendors. On the one hand, low wage countries enable new opportunities to offer services at low costs. On the other hand, however, vendors can not neglect the importance of physical closeness to markets and potential customers. In this paper we present a model and prototype to support location planning for IT service vendors. The model is based on the warehouse location problem which is well known from the field of logistics.     

移动分布式环境下服务适配系统研究

移动环境给分布式资源共享特别是服务发现和资源定位带来了新的挑战。本文分析了移动性给服务发现和资源定位机制带来的特殊性，介绍了具有服务主动适配能力的服务适配原型系统Service CatalogNet，给出了其中的关键技术：适应移动性需求的支持多样性的服务模型、服务主动适配策略以及基于模糊匹配的服务定位机制。     

HLLS: A History information based Light Location Service for MANETs

In mobile ad hoc networks, a location service (LS) provides the fundamental service for geographical routing. However, most existing schemes for location service incur a high overhead because of the periodic updates of location information. To address this issue, we propose a novel History information based Light Location Service (HLLS), using the temporal relationship among historical locations of mobile nodes in the network. In HLLS, location information of mobile nodes is propagated by Hello beacons locally, and the location query is performed with the aid of historical locations. In this way, HLLS can eliminate the tremendous periodical location updates and significantly reduce the overhead for location service. Using a combination of analytical modeling and extensive simulations, we show the effectiveness of HLLS in comparison with other approaches.