Handling recoverable temporal violations in scientific workflow systems: a workflow rescheduling based strategy

Due to the complex nature of scientific workflow systems, the violations of temporal QoS constraints often take place and may severely affect the usefulness of the execution's results. Therefore, to deliver satisfactory QoS, temporal violations need to be recovered effectively. However, such an issue has so far not been well addressed. In this paper, we first propose a probability based temporal consistency model to define the temporal violations which are statistically recoverable by light-weight exception handling strategies. Afterwards, a novel Ant Colony Optimisation based two-stage workflow local rescheduling strategy (ACOWR) is proposed to handle detected recoverable temporal violations in an automatic and cost-effective fashion. The simulation results demonstrate the excellent performance of our handling strategy in reducing both local and global temporal violation rates.