A Dynamic Agent-Based Web Service Invocation Infrastructure

Web services have led a revolution of Internet technology architecture by their platform-independence, language- independence and other characters. But traditional Web service architecture is based on "Client/Server" model, where server is always providing service reactively. Software agents are now increasingly used in commercial applications to solve complex engineering problems, for their autonomous, proactive and social capabilities. And these applications often make use of Web services. As such, this paper presents a Web service invocation infrastructure based on software agents. The infrastructure is a hybrid peer-to-peer model, using agents to describe service providers and service customers. This invocation model is more flexible than traditional Web service model, for (l)agents can invoke services in a proactive manner no matter whether they act like service customers or providers, and(2)agents can also act as multi-role actors in service domain. And with inspiration from Aspect-Oriented programming, web services are mapped as aspects, while agents are mapped as node. In this way, Web service policies in an agent can be considered to be form an filter chain, either incoming filter chain or outgoing filter chain, which is used to describe agent's request or response filter policies. When service contractor satisfies both the incoming filter chain and the outgoing filter chain at the same time, the corresponding service can be invoked dynamically. And experiments show that dynamic service invocation can be achieved in our infrastructure.