Improve the service quality of multi-agent system : ontology management

Abstract

Multi-agent model has become very popular in the distributed environment in recent years. In order to fully realize its potentials, many studies have focused on improving the service quality related issues such as security, standardization, open environment architecture, integration with existing system, and discovery of services. In this thesis, we mainly investigate issues related improving quality in service discovery. Service discovery is the use of designated agent directory server for agents to locate their required agent services autonomously based on the nature of tasks required by agents. Currently, directory services only provide run-time binding for an agent to a predefined agent service of which the agent has complete knowledge before hand. However there is a lack of discovery service at development cycle. There is no sufficient mechanism for an agent service to declare or export its functionalities on-line through the Internet so as to facilitate the development of agent applications. On the other hand, the client agent application development may be limited to a closed proprietary environment where the developer follows the service-provider-defined specification to implement the application. In this work, we extend service discovery to the development cycle. By using the provision of ontology and ontology management, the specification of agent services are linked to ontology, enhancement to services are also kept track of through version controls in ontology management. In addition, agents can declare its required services through a language using a defined version the ontology Thus making it possible for new service providers to serve exists clients as needed services are declared explicitly The technology developed involves locating relevant ontology, accessing and storing the ontology, keeping track of ontology changes, declaration of service through ontology, mapping services to implementation, automatic and semi-automatic wrapping for different versions of services and finally, at run-time, the binding of agents to services and online directory service for agent mapping with respect to a service type.