Modeling And Analyzing Of The Intelligent Web Services Composition

With the rapid development of the Internet, a single web service function can notmeet users’ requirements. We need to combine multiple web services to provide morepowerful features. Although the web services composition has made some progress,there is no general technology framework of web service to implement automaticoperation, self-interaction and dynamic integration of services. Mobile agenttechnology is the combination product of distributed technology and artificialintelligence technology. It has such advantages as autonomous behavior and naturalmodeling. It can migrate independently in the heterogeneous network. This paperapply mobile agent to the field of the web services composition, in order to providenovel ways of developing dynamic services composition and heterogeneous softwaresystems deployed in Internet.This paper combines the web services composition and mobile agent technology,and proposes a hierarchical structure of web services dynamic composition based onmobile agent. The main contribution of this paper is introduced as following:(1) Modeling the formal model of the web services composition based onhigh-level Petri net.The model of the system includes three layers: system service layer, mobileagent layer and security layer. First, we use the high-level Petri net to establish theformal models of the system layer and agent layer respectively. Then the securityissue of the system is discussed and security model is designed to protect the host.The model clearly describes the process of service interaction and fully embodies themobility, autonomy of mobile agent and the controllability of system layer. The modelreduces network load, enhances the capacities of interaction and dynamic adaptationof web services.(2) The formal verification method is proposed to verify the correctness of themodel.This paper uses SPIN, the popular tool for model detecting, to verify model andlists the transfer rules from Petri net model to Promela model. It describes theproperties of system by using LTL and simulates and validates a model based on SPIN.A distingushing merit of our method is the scale of the model checking can be reduced, and the efficiency of model checking can be improved.(3) Investigating the Application of the formal model and model checkingmethod on a case study.An example of the web information services system is designed and analyzed.The system is first modeled by using the method in the paper, then we verify andanalyze the properties and security of system. The example shows and explains thehigh feasibility and effectiveness of the proposed method.