A Petri Net Approach to Reliable Execution for Web Service Composition

With development of SOA, the complex problem can be solved by combining available individual services and ordering them to best suit user´s requirements. Web services composition is widely used to business environment. With the features of inherent autonomy and heterogeneity for component Web services it is difficult to predict the behaviors of the overall composite service. Therefore, transactional properties and non-functional quality of service (QoS) properties are crucial for selecting the web services to take part in the composition. Transactional properties ensure reliability of composite Web service, and QoS properties can identify the best candidate web services from a set of functionally-equivalent services. In this paper we define a Colored Petri Net (CPN) model which involves transactional properties of Web services in the composition process. To ensure reliable and correct execution, unfolding processes of the CPN are followed. The execution of transactional composition Web service (TCWS) is formalized by CPN properties.