7 - Temporal Checkpoint Selection and Temporal Verification

Abstract

After temporal constraints are assigned at build time, the temporal consistency states of workflow execution are to be monitored at run-time. As the first step in the temporal consistency monitoring component, temporal checkpoint selection is to select the activity points where temporal verification is required to be conducted to detect temporal violations. Therefore, the overall time overheads and monetary cost for delivering high temporal QoS are highly related to the number of selected checkpoints along scientific cloud workflow execution. After checkpoint selection, as the second step in the temporal consistency monitoring component, temporal verification is to verify the current temporal consistency states to evaluate the level of the detected temporal violation and obtain the input data for the subsequent actions such as temporal violation handling. Based on the same temporal consistency model, temporal checkpoint selection and temporal verification are usually discussed together for the detection of temporal violations. Therefore, for the ease of discussion and to avoid the redundancies of the technical content, this chapter addresses temporal checkpoint selection together with temporal verification. This chapter introduces the minimum probability time redundancy-based temporal checkpoint selection strategy and the probability temporal consistency-based temporal verification. This chapter is organised as follows. Section 7.1 presents the specifically related work and problem analysis. Section 7.2 presents the probability time redundancy-based temporal checkpoint selection and temporal verification strategy. Section 7.3 demonstrates the evaluation results.