Context: Web Services are emerging technologies that enable application to application communication and reuse of autonomous services over Web. Composition of web services is a concept of integrating individual web services to conduct complex business transactions based on functionality and performance constraints Objective: To satisfy user requirements, technologies of Quality of service (QoS)-based web service composition (QWSC) are widely used to build complex applications by discovering the best-fit web services in term of QoS. Method: In this paper, a QoS-based service selection (RQSS) algorithm is proposed to help composite web application development by discovering feasible web services based on functionalities and QoS criteria of user requirements. The RQSS recommends prospective service candidates to users by relaxing QoS constraints if no suitable or available web service could exactly fulfill user requirements. Results: A generic framework is implemented to demonstrate the feasibility and performance of RQSS by adapting WS-BPEL standards, and can be reused for QoS-based web composition applications. Conclusion: The experimental results show that the RQSS algorithm indeed performs well and increases the system availability and reliability.

https://ir.nctu.edu.tw:443/bitstream/11536/14623/1/000296986900006.pdf

A relaxable service selection algorithm for QoS-based web service composition

The current evolution of Ubiquitous Computing and of ServiceOriented Computing is leading to the development of context-aware services. Context-aware services are services whose descriptio n is enriched with context information related to the service execution enviro nment, adaptation capabilities, etc. This information is often used f or discovery and adaptation purposes. However, context information is naturally dynamic and incomplete, which represents an important issue when comparing service description and user requirements. Actually, uncertainty of context information may lead to inexact matching between provided and required serv ice capabilities, and consequently to the non-selection of services. In o rder to handle incomplete context information, we propose in this paper a gra ph-based algorithm for matching contextual service descriptions using simi larity measures, allowing inexact matches. Service description and requiremen ts are compared using two kinds of similarity measures: local measures, which compare individually required and provided properties (represented as gr ph nodes), and global measures, which take into account the context descr iption as a whole, by comparing two graphs corresponding to two context d scriptions.

Context-aware service selection using graph matching

Context-aware systems are applications that adapt themselves to several situations involving user, network, data, hardware and the application itself. In this paper, we review several context models proposed in different domains: content adaptation, service adaptation, information retrieval, etc. The purpose of this review is to expose the representation of this notion semantically. According to this, we propose a framework that analyzes and compares different context models. Such a framework intends helping understanding and analyzing of such models, and consequently the definition of new ones. This framework is based on the fact that context-aware systems use context models in order to formalize and limit the notion of context and that relevant information differs from a domain to another and depends on the effective use of this information. Based on this framework, we consider in this paper a particular application domain, Business Processes, in which the notion of context remains unexplored, although it is required for flexibility and adaptability. We propose, in this paper, an ontology-based context model focusing on this particular domain.

/pdf/semantic-representation-of-context-models-a-framework-for-3ox3hmsh3t.pdf

Semantic representation of context models: a framework for analyzing and understanding

Services in the next generation Internet, Universal Network, is distinct from that in the current network. The reason is that the former has QoS (quality of sevice) grading. In the universal network, different services have different QoS; therefore, service discovery in the Universal Network is quite distinct from that of the present network. In this paper, we put QoS measurement into service discovery so as to adapt to Universal Network. A lot of research works adopt semantic web technology, OWL-S (web ontology language for services), which is innovative for service discovery. For the purpose of service discovery in Universal Network, we append QoS descriptions to OWL-S. Such OWL-S with QoS information is called OWL---QoS, which is the groundwork for service discovery in the Universal Network. Secondly, we present a matching algorithm that allows matching on the basis of capabilities and QoS descriptions of services. Moreover, we also adopt P2P as an infrastructure to fulfill the service discovery because of the large amount of services in the network.

Bring QoS to P2P-based semantic service discovery for the Universal Network

Artificial intelligence in service-oriented software design

In the last few years telecommunications and Internet have spread all over the world, in a pervasive way, connecting millions of devices, people, sensors and services without a planned strategy. In such scenario the discovery of services represent still an open challenging research field. To address that problem this paper proposes a context-aware semantic service discovery architecture designed to perform distributed service discovery in heterogeneous networks. This novel architecture is technology independent and compatible with most of the existent service discovery protocols; it inherits and extends the results of the last research groups in the field of context-aware service discovery based on the use of semantic languages. The present work presents the first results of the service discovery design activity which has been carried out within DAIDALOS II (Designing Advanced network Interfaces for the Delivery and Administration of Location independent, Optimised personal Services), a project granted in the European 6th Framework Research Programme, within the IST (Information Society and Technology) thematic area.

A. Aiuto

Papers

Context-aware Semantic Service Discovery