Handling concurrency control problem in web service compositions

Business applications are built by composing the pre-existing services, which are executed across multiple loosely-coupled organizations. An important challenge during composition of services is to ensure consistency of information modified by concurrently executing component services. In a web service transaction environment involving long running business processes, atomicity and isolation cannot be ensured. In order to ensure the relaxed atomicity of Transactional Composite Services (TCS), relaxed atomicity models have been proposed, but none of them handle concurrency control problem which may lead to inconsistent results when multiple TCSs run concurrently. Hence, a concurrency control algorithm based on I/O dependencies among services has been proposed in this paper, to eliminate inconsistencies caused by concurrent execution of TCSs.