Xiao Liu PhD Thesis.pdf - Faculty of Information and Communication ...

negotiation process between service users and service providers based on either a
time oriented or probability oriented manner. When the coarse-grained temporal
constraints are set, the fine-grained temporal constraints for each individual
workflow activities can be derived and propagated in an automatic fashion.
Therefore, the time overheads and computation cost for temporal constraints setting
are much smaller compared with conventional manual settings. The effectiveness of
the strategy is demonstrated through a case study.
COMPONENT II consists of Chapter 6.
In Chapter 6, the existing state-of-the-art checkpoint selection and temporal
verification strategy is modified to adapt to our probability based temporal
consistency model so that only one type of checkpoint needs to be selected instead
of previous multiple types, and only one type of temporal consistency state needs to
be verified instead of previous multiple types. Accordingly, the minimum
probability time redundancy based checkpoint selection strategy and probability
temporal consistency based temporal verification strategy are provided. The
mathematical proof has demonstrated that our adapted strategy is of the same
necessity and sufficiency as the existing state-of-the-art checkpoint selection
strategy but with better cost-effectiveness.
COMPONENT III consists of Chapter 7 and Chapter 8.
In Chapter 7, an adaptive temporal violation handling point selection strategy is
proposed. Temporal violation handling point selection is a novel idea of our latest
study on workflow temporal verification. Based on the necessary and sufficient
checkpoints, temporal violation handling point selection is to further select a subset
of these checkpoints where the probability of temporal violations is higher than the
specific threshold, i.e. temporal violation handling is indeed necessary. Motivated by
adaptive testing techniques and requirements of cost-effectiveness, our temporal
violation handling point selection strategy can select much fewer violation handling
points than conventional strategies while maintaining satisfactory temporal QoS. In
such a case, the overall cost for handling temporal violations can be significantly
reduced.
In Chapter 8, an overview of temporal violation handling strategies is presented.
Given the basic requirements of automation and cost-effectiveness, we design a
general light-weight two-stage local workflow rescheduling strategy which features
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