Modeling snapshot of composite WS execution by colored petri nets

Abstract

The global transactional property of a Transactional Composite Web Service (TCWS) allows recovery processes if a Web Service (WS) fails during the execution process. The following actions can be performed if a WS fails: retry the faulty WS, substitute the faulty WS, or compensate the executed WSs. In consequence, these fault-tolerance mechanisms ensure the atomicity property of a TCWS with an all-or-nothing endeavor. In this paper, we present a formal definition of a checkpointing approach based in Colored Petri-Nets (CPNs) properties, in which the execution process and the actions performed in case of failures rely on unrolling processes of CPNs. Our checkpointing approach allows to relax the atomic transactional property of a TCWS in case of failures. The all-or-nothing transactional property becomes to the something-to-all property. A snapshot of the most possible advanced partial result is taken in case of failures and it is returned to the user (user gets something), providing the possibility of restarting the TCWS from an advanced execution state to complete the result (user gets all later), without affecting its original transactional property. We present the execution algorithms with the additionally capacity of taking snapshot in case of failures and experimental results to show the reception of partial outputs due to the relaxation of the all-or-nothing property. © Springer-Verlag 2013.