Failure Handling and Coordinated Execution of Concurrent Workflows

Work ow management systems (WFMSs) coordinate the execution of applications distributed over networks. In WFMSs, data inconsistencies can arise due to (i) the interaction between steps of concurrent threads within a work ow (intra-work ow coordination) (ii) the interaction between steps of concurrent work ows (interwork ow coordination) and (iii) the presence of failures. Since these problems have not received adequate attention, this paper focuses on developing the necessary concepts and infrastructure to handle them. First, to deal with interand intrawork ow coordination requirements we have identi ed a set of high level building blocks. Secondly, to handle failures we propose a novel and pragmatic approach called opportunistic compensation and re-execution that allows a workow designer to customize work ow recovery from correctness as well as performance perspectives. Thirdly, based on these concepts we have designed a work ow speci cation language that expresses new requirements for work ow executions and implemented a run-time system for managing work ow executions while satisfying the new requirements. These ideas are geared towards improving the modeling and correctness properties o ered by WFMSs and making them more robust and exible.