ACTIVITY COMPLETION DURATION BASED CHECKPOINT SELECTION FOR DYNAMIC VERIFICATION OF TEMPORAL CONSTRAINTS IN GRID WORKFLOW SYSTEMS

摘要

In grid workflow systems, to verify temporal constraints efficiently at the run-time execution stage, some checkpoints are selected such that temporal verification need only be conducted at those checkpoints rather than at all activity points. However, existing typical checkpoint selection strategies may ignore some necessary checkpoints and select some unnecessary ones. This eventually impacts overall temporal verification effectiveness and efficiency. To improve such status, in this paper, we develop a new checkpoint selection strategy. Specifically, we first investigate the relationships between activity completion duration and the consistency of temporal constraints. Then, based on those relationships we present our new checkpoint selection strategy. Our new strategy can avoid the omission of necessary checkpoints and the selection of excess unnecessary checkpoints. Consequently, it can achieve better temporal verification effectiveness and efficiency than the existing typical checkpoint selection strategies. The final comparison and quantitative evaluation further demonstrate this result.