Agent-based service composition has provided a promising computing paradigm for the automatic web service composition. In this paper, a formal service agent model is proposed, which integrates the web service and software agent technologies into one cohesive entity. Based on the service agent model, a distributed planning algorithm for web service composition called DPAWSC is presented. DPAWSC formalizes web service composition into a graph search problem according to the dependence relations among service agents. The key to DPAWSC is that the alternative solution with smaller length has higher priority to be searched than one with larger length. DPAWSC is based on the distributed decision making of the autonomous service agents and addresses the distributed nature of web service composition. We evaluate the algorithm by simulation experiments and the results demonstrate that DPAWSC is effective for its ability to produce the high quality solution at a low cost of communications.

An agent-based Web service workflow model is presented in this paper to facilitate the autonomic Web service composition, which contains three layers. The top is the user layer which represents the service requirements as goal workflow, the bottom service layer denotes the distributed Web services, and the middle is the agent layer. Each service agent in the agent layer abstracts the features of a group of actual operations with similar functions as operation template and models the process of using operation templates to achieve a certain goal as plan. The proposed model has great flexibility and extensibility and provides the guidance for the development of Web service integration tools.

One of the challenging problems that Web service technology faces is the ability to rapidly locate useful on-line services based on their capabilities. With the increasing popularity of Web services, a wide variety of services are offered that can satisfy the functional requirements of a special task, therefore there is need for mediation infrastructures able to support humans or agents in the eventual selection of appropriate services. To address this problem, a fuzzy multi-attribute decision making algorithm for Web services selection based on quality of service is proposed, which can select the most appropriate one with the highest degree of membership belonging to the positive ideal solution. The experimental results indicate that the fuzzy multi-attribute decision making algorithm proposed in this paper outperforms the random and round robin selection policies

The rapid popularity of wireless networks and portable devices spurs mobile users to access various information services. Service provision in ubiquitous computing has become a challenging issue. In this paper, we present a user-centric service provision model (TJCSPM). UCSPM is designed to support user-oriented quality of service (QoS) evaluation and dynamic service delivery, according to various contexts such as device capability, network status and user preference, etc. Unlike most service provision middleware, UCSPM can provide appropriate services to mobile users, which are not only suitable for being delivered to resource-limited environments, but also with a high degree of satisfaction of users. We have developed a prototype of context-aware expo assistant application to demonstrate the effectiveness of UCSPM.