Semantic Web service discovery: state-of-the-art and research challenges

Ubiquitous computing paradigms involving social agents require principled selection of services, context-aware analysis, and satisfaction of requests, as well as dynamic interaction and negotiation with other agents. Synergies between semantic technologies and service discovery facilitate rich and formal representations of services and agent interactions as well as specialization and generalization of service needs. In this paper, we provide an extensive review of semantic Web service discovery, highlighting the state-of-the-art approaches, the key semantic formalisms employed, as well as benchmarks and testbeds for performance evaluation. Defining a generic framework for semantic service discovery, we describe the key tasks and criteria involved in agent-based computing. A detailed comparison of the popular discovery systems is performed with a discussion on trade-offs between existing approaches. We conclude by pointing out important research challenges to be addressed for next-generation service discovery by dynamic multi-agent systems in complex environments.     

COCOA: COnversation-based service COmposition in pervAsive computing environments with QoS support

Pervasive computing environments are populated with networked services, i.e., autonomous software entities, providing a number of functionalities. One of the most challenging objectives to be achieved within these environments is to assist users in realizing tasks that integrate on the fly functionalities of the networked services opportunely according to the current pervasive environment. Towards this purpose, we present COCOA, a solution for COnversation-based service COmposition in pervAsive computing environments with QoS support. COCOA provides COCOA-L, an OWL-S based language for the semantic, QoS-aware specification of services and tasks, which further allows the specification of services and tasks conversations. Moreover, COCOA provides two mechanisms: COCOA-SD for the QoS-aware semantic service discovery and COCOA-CI for the QoS-aware integration of service conversations towards the realization of the user task’s conversation. The distinctive feature of COCOA is the ability of integrating on the fly the conversations of networked services to realize the conversation of the user task, by further meeting the QoS requirements of user tasks. Thereby, COCOA allows the dynamic realization of user tasks according to the specifics of the pervasive computing environment in terms of available services and by enforcing valid service consumption.     

Enhanced service discovery in Bluetooth

The rapid evolution and expansion of wireless-enabled environments have increased the need for sophisticated service discovery protocols (SDPs). Typically, service discovery involves a client, service provider, and lookup or directory server. The paper discusses Bluetooth (http://www.bluetooth.com) short-range wireless technology. The Bluetooth protocol stack includes specifications that define the SDP, RFCOMM (for cable replacement), the logical link control and adaptation protocol (L2CAP), a host controller interface (HCI), the link manager protocol (LMP), the base-band protocol, and a radio frequency (RF) protocol. The paper considers Bluetooth service discovery improvements with semantic matching     

基于语义的服务发现技术研究综述

语义Web服务是Web服务的语义扩展,它能够有效地提高服务发现的效率,并使得实现服务发现自动化成为可能。基于语义的服务发现是语义Web服务技术的核心,其关键技术包括标识语义的Web服务描述语言、基于语义的服务发现体系结构和基于语义的服务匹配算法。本文分别从这三个方面对目前基于语义的服务发现技术进行了详细的分析比较。文章最后对基于语义的Web服务发现技术进行了总结与展望。     

Service discovery in pervasive computing environments

Pervasive computing environments pose unique service discovery challenges. We have developed a taxonomy of existing protocols as a basis for analyzing their approaches and identifying problems and open issues relative to service discovery in pervasive computing environments.     

基于本体映射的语义Web服务发现框架

分析了语义Web服务中存在的本体异构问题,讨论了语义Web服务发现中输入、输出匹配的方法,以及本体映射中概念相似度计算方法.在已有的Web服务模型基础上,引入语义Web服务发现的机制,提出了一个基于本体映射的语义Web服务发现框架,并阐述了其实现机制.该框架下的本体映射技术的应用能够增强语义Web服务发现的能力.     

基于向量空间的Web服务发现模糊方法

Web服务已逐渐发展成为重要的分布式计算范式。在综合分析了现有的Web服务描述文档的基础上,提出了一种基于模糊集的服务特征项集选取算法以及Web服务向量空间的生成方法。利用生成的向量空间,对Web服务进行模糊聚类。基于此,文中给出了向量空间中进行Web服务发现的模糊方法。所提出的方法只需利用现有的Web服务描述信息,保证了服务发现的有效性。     

Facilitating Service Discovery with Semantic Overlay

Service Oriented Architecture （SOA） and Peer-to-Peer （P2P） computing share many common characteristics. It is believed that the combination of the two emerging techniques is a very promising method in promoting the web services （WS）. Because the service discovery plays a key role in the integration, here a P2P-based framework to manage the knowledge of service and locating services is proposed. In this paper, the details of the principle, constructing and maintaining of service semantic overlay architecture have been described, and the way how the semantic overlay facilitates discovery of service resources is illustrated. To enable the semantic web service superiority, Service Ontology, which is considered as the service semantic model, is employed to depict service. The service discovery includes two phases： searching on the service semantic overlay; and local discovery in peer＇s service repository. Various solutions have been proposed to realize those two phases. Furthermore, tests are carried out to evaluate service discovery on the architecture.     

An incentive compatible reputation mechanism for ubiquitous computing environments

The vision of ubiquitous computing is becoming a reality thanks to the advent of portable devices and the advances in wireless networking technologies. It aims to facilitate user tasks through seamless utilization of services available in the surrounding environments. In such distributed environments featuring openness, interactions such as service provision and consumption between entities that are unknown or barely known to each other, are commonplace. Trust management through reputation mechanism for facilitating such interactions is recognized as an important element of ubiquitous computing. It is, however, faced by the problems of how to stimulate reputation information sharing and enforce honest recommendation elicitation. We present in this paper an incentive compatible reputation mechanism to facilitate the trustworthiness evaluation of entities in ubiquitous computing environments. It is based on probability theory and supports reputation evolution and propagation. Our reputation mechanism not only shows robustness against lies, but also stimulates honest and active recommendations. The latter is realized by ensuring that active and honest recommenders, compared to inactive or dishonest ones, can obtain the most number of honest (helpful) recommendations and thus suffer the least number of wrong trust decisions, as validated by simulation based evaluation. The proposed reputation mechanism is also implemented as part of a QoS-aware Web service discovery middleware and evaluated regarding its overhead on service discovery latency.     

普适计算环境下服务发现问题的研究与进展

普适计算环境下,环境的结构、组成以及环境中的资源、服务都是动态变化的,而服务发现技术能够在动态变化的普适计算环境中动态查找、定位所需的服务,是解决普适计算环境异构性、实现不同应用集成的有效途径,因此逐渐成为普适计算中研究的一个热点和重点。基于此,本文总结、分析了当前已有的比较著名的普适计算服务发现协议并进行了分类比较,总结了各个方向上目前的研究进展,在此基础之上对今后的研究趋势进行了分析与展望。     

METEOR-S WSDI: A Scalable P2P Infrastructure of Registries for Semantic Publication and Discovery of Web Services

Web services are the new paradigm for distributed computing. They have much to offer towards interoperability of applications and integration of large scale distributed systems. To make Web services accessible to users, service providers use Web service registries to publish them. Current infrastructure of registries requires replication of all Web service publications in all Universal Business Registries. Large growth in number of Web services as well as the growth in the number of registries would make this replication impractical. In addition, the current Web service discovery mechanism is inefficient, as it does not support discovery based on the capabilities of the services, leading to a lot of irrelevant matches. Semantic discovery or matching of services is a promising approach to address this challenge. In this paper, we present a scalable, high performance environment for Web service publication and discovery among multiple registries. This work uses an ontology-based approach to organize registries into domains, enabling domain based classification of all Web services. Each of these registries supports semantic publication and discovery of Web services. We believe that the semantic approach suggested in this paper will significantly improve Web service publication and discovery involving a large number of registries. This paper describes the implementation and architecture of the METEOR-S Web Service Discovery Infrastructure, which leverages peer-to-peer computing as a scalable solution.     

Service-oriented smart home applications: composition, code generation, deployment, and execution

A smart home usually has a variety of devices or home appliance, instead of designing software for a specific home, this paper proposes a service-oriented framework with a set of ontology systems to support service and device publishing, discovery of devices and their services, composition of control software using existing control services that wrap devices, deployment, and execution of the composed service in an computing environment, monitoring the execution, and recovery from device failure. The ontology systems specify semantic information about devices, services, and workflows used in various smart home, and users can compose and recompose services for their specific needs. New devices, workflows, and services can be added into ontology. Most of the steps in this process can be automated including code generation. For example, service composition will be carried out in three steps: abstract workflow design, function construction, and device discovery, and different codes can be generated for different computing platforms such as Java and Open Services Gateway initiative environments. In this way, a variety of smart home can be constructed rapidly using the framework by discovery and composition using existing services and workflows. This paper illustrates this framework using a media control example to illustrate the ontology, discovery, composition, deployment, execution, monitoring, and recovery.     

基于推理和相似度计算的语义Web服务匹配策略

将本体的概念引入Web服务提升了服务的语义表达能力和发现能力,传统的语义Web服务匹配主要有基于推理和基于本体相似度计算两种方式.基于推理的服务匹配较容易实现,具有稳定的查准率和较高的运行效率,但同一级结果间不能进一步区分结果的匹配度.基于相似度计算的服务发现可以精确地描述结果与查询条件的匹配程度,便于用户比较,但实现较为复杂,并且在最坏情况下有糟糕的响应时间.在基于推理的服务匹配策略的基础上,提出了一种带有语义相似度计算的服务匹配策略,并用一个书籍领域本体的匹配实例进行了说明.     

A semantic interoperability framework for software as a service systems in cloud computing environments

In cloud computing environments in software as a service (SaaS) level, interoperability refers to the ability of SaaS systems on one cloud provider to communicate with SaaS systems on another cloud provider. One of the most important barriers to the adoption of SaaS systems in cloud computing environments is interoperability. A common tactic for enabling interoperability is the use of an interoperability framework or model. During the past few years, in cloud SaaS level, various interoperability frameworks and models have been developed to provide interoperability between systems. The syntactic interoperability of SaaS systems have already been intensively researched. However, not enough consideration has been given to semantic interoperability issues. Achieving semantic interoperability is a challenge within the world of SaaS in cloud computing environments. Therefore, a semantic interoperability framework for SaaS systems in cloud computing environments is needed. We develop a semantic interoperability framework for cloud SaaS systems. The capabilities and value of service oriented architecture for semantic interoperability within cloud SaaS systems have been studied and demonstrated. This paper is accomplished through a number of steps (research methodology). It begins with a study on related works in the literature. Then, problem statement and research objectives are explained. In the next step, semantic interoperability requirements for SaaS systems in cloud computing environments that are needed to support are analyzed. The details of the proposed semantic interoperability framework for SaaS systems in cloud computing environments are presented. It includes the design of the proposed semantic interoperability framework. Finally, the evaluation methods of the semantic interoperability framework are elaborated. In order to evaluate the effectiveness of the proposed semantic interoperability framework for SaaS systems in cloud computing environments, extensive experimentation and statistical analysis have been performed. The experiments and statistical analysis specify that the proposed semantic interoperability framework for cloud SaaS systems is able to establish semantic interoperability between cloud SaaS systems in a more efficient way. It is concluded that using the proposed framework, there is a significant improvement in the effectiveness of semantic interoperability of SaaS systems in cloud computing environments.     

基于语义的QoS感知Web服务发现机制

随着提供相同功能的Web服务数量的日益增多,服务质量(Quality of Service,QoS)成为用户选择Web服务的重要考虑因素.目前,通过对服务QoS属性在语法层匹配来提供Web服务选取的机制不能很好地满足复杂QoS属性匹配的要求.研究了基于用户QoS需求偏好,将用户需求的QoS与候选服务的QoS进行语义比较,结合约束规划(Constraint Programming)方法,在语义层匹配Web服务的QoS属性,选取满足匹配要求的服务,最后对满足QoS属性值约束的候选服务进行优化选择处理,获取最终匹配的候选服务.     

基于历史调用日志分析的Web服务间语义相关性发现

针对Web服务间语义相关性发现这一Web服务领域研究的关键问题,目前的方法不能较好地描述服务间语义相关的不确定性,进而不能有效地支持自动服务发现与组合.以Web服务描述中的操作作为服务组件,首先给出Web服务调用历史日志的定义,接着以统计计算为手段,基于PageRank算法给出服务组件权重的计算方法,进一步基于静电场理论给出Web服务组件间语义相关度的度量方法,为Web服务搜索、发现与组合奠定基础.实验结果表明,该方法具有高效性和实用性.     

基于服务簇的空间信息服务自动发现

现有Web服务自动发现方法中存在服务匹配程度区分不明显、服务发现精度不高等问题。为此,提出一种基于服务簇的空间信息服务自动发现算法。对发布的空间信息服务进行聚类分析,计算服务请求与各服务簇中心的相似度,由此确定最优匹配簇,根据服务请求与最优匹配簇中服务的语义相似度,得出服务请求的最优匹配服务。实验结果表明,该算法在实现对Web服务匹配程度定量表示的同时,能有效提高匹配程度的区分度和服务发现的查全率和效率。     

Trustworthy assurance of service interoperation in cloud environment

Cloud computing can be realized by service interoperation and its essence is to provide cloud services through network. The development of effective methods to assure the trustworthiness of service interoperation in cloud environment is a very important problem. The essence of cloud security is trust and trust management. Combining quality of service (QoS) with trust model, this paper constructs a QoS-aware and quantitative trust-model that consists of initial trust value, direct trust value, and recommendatory trust value of service, making the provision, discovery, and aggregation of cloud services trustworthy. Hence, it can assure trustworthiness of service interoperation between users and services or among services in cloud environment. At the same time, based on this model, service discovery method based on QoS-aware and quantitative trust-model (TQoS-WSD) is proposed, which makes a solid trust relationship among service requestor, service provider and service recommender, and users can find trustworthy service whose total evaluation value is higher. Compared to QoS-based service discovery (QoS-WSD) method, it is proved by the experiment for TQoS-WSD method that more accurate result of service discovery will be achieved by service requestor, while reasonable time cost is increased. Meanwhile, TQoS-WSD method strongly resists the effect of service discovery by untrustworthy QoS values and improves service invocation success-rate and thus assures trustworthiness of services interoperation.