/spl pi//sub RBT/-calculus compensation and exception handling protocol

Several existing research protocols have already studied long running transactions within a formal context and many of them seemed to use concepts which are not suitable. However, there still exists a great challenge to perform transactions in the loosely coupled environment. In this paper, we present formal model for compositional protocol with the asynchronous /spl pi/-calculus with compensation and exception handling. We study the practice of /spl pi//sub RBT/-calculus, by discussing few paradigmatic examples, its theory, by defining semantics and providing a correct encoding of /spl pi//sub RBT/-calculus into asynchronous /spl pi/-calculus. /spl pi//sub RBT/-calculus is a business process modeling protocol and a distinctive feature of the language is its support for compensation. Compensation is an action taken to recover from error or cope with a change of plan, especially when rollback of a process is not possible. We also propose a process-oriented transactional business coordination model with hierarchical structure. It allows dependencies across hierarchies and supports various transactional behaviors of different services. Based on this model, a novel failure recovery algorithm is presented. It can ensure semantic atomicity for long running Web services composition. Analysis shows it can effectively reduce compensation sphere and thus decrease costs.