Contracting of E-business Services in a Constraint-Based Process Modeling Framework

Analyzing and contracting of E-Business service processes is a crucial step between discovery and execution of Semantic Web Services. This paper proposes a service modelling framework consists of constraint-based service contract, agent style communication messages and service process specification. Service contract is used as shared knowledge between participants and instrument for advertising and requesting of services. The Constraint Process S pecification proposed is capable of describing complex data and control-flow restrictions as well as data content restrictions. A state transition based operational semantic for this framework is given. A virtual machine is built for analyzing and contracting of services. We illustrate the expressiveness of this framework within an online shopping scenario.