A Model for Web Service Coordination in Long-Running Transactions

With the growth of interest on service oriented applications (SOAs), a key aspect of aggregating business processes and web services is the transactional support for SOAs. The classical notion of transaction denotes a unit of work that is atomic, consistent, isolated and durable. However, in the context of service oriented computing, transactions may require long periods to complete and the traditional mechanisms are not always appropriate. The development of SOAs should be based on models of computation in which there is a clear separation between coordination and computation features. In this paper we propose a computational model called transactional constraint automata (TNCA). The model describes a collection of services that interact via common transaction labels. Each transaction is an interaction described via a Reo circuit. Thus our model achieves a separation of coordination and computation: the set of automata depicts the control flow and the internal behavior of different services and business processes, while the non-atomic interactions among services are captured by the common transactions via Reo circuits.