From Theory to Practice in Transactional Composition of Web Services

We address the problem of composing Web Services in long-running transactional business processes, where compensations must be dealt with appropriately. The framework presented in this paper is a Java API called Java Transactional Web Services (JTWS), which provides suitable primitives for wrapping and invoking Web Services as activities in long-running transactions. JTWS adheres to a process calculi formalisation of long-running transactions, called Sagas, which fixes unambiguously the implemented compensation policy. In particular, the primitives provided by JTWS are in one-to-one correspondence with the primitives of Sagas, and they are abstract enough to hide the complex details of their realization, thus favouring usability. Moreover, JTWS orchestrates business processes in a distributed way