Web services discovery based on the trade-off between quality and cost of service

Abstract

A Web service is an autonomous unit of application logic that provides either some business functionality or information to other applications through an Internet connection. Web services discovery is the process of finding most appropriate Web services providers needed by a Web services requestor. One of the important issues in the discovery process is for Web services providers and Web services requestors to negotiate and find an integrative solution that is optimal to both sides. Web services providers use resources to provide services to requestors in return for benefits. On the other hand, Web services requestors pay for services from providers in return for benefits as well. In this scenario, both parties should have their own cost-benefit models for making such a business decision. In convention, fixed pricing strategies are used for Internet-related business models such as online bookstores. However, these may not be suitable in some business models. For example, data mining services are always one-of-a-kind services, expensive and non-repetitive that usually require a more sophisticated business model. Therefore, sophisticated Web services providers should provide a list of trade-off alternatives between the Quality of Service (QoS) they offer and the Cost of Service (CoS) they use to requestors. In this model, the QoS relates to performance-oriented capabilities and the CoS relates to services' resource requirements. To achieve an integrative solution, both parties have to evaluate the list of QoS and CoS alternatives for obtaining an appropriate combination. One of the negotiation strategies for achieving integrative solutions is called logrolling. Traditionally logrolling in two-issue (i.e., the QoS and CoS) and two-party (i.e., the Web services provider and requestor) negotiation is defined as the exchange of loss in one issue for gain in other issues that result in an increase of the overall values for both parties. It means that each party can increase the overall value by trading the less preferred issue for the more preferred, provided that a trade-off ratio is satisfactory. This paper presents a token-based approach to quantify the QoS and CoS for achieving integrative solutions.