Estimating Upper Bound of Duration for Instances of Generalized Well-Formed Workflow

Estimating upper bound of duration for workflow instances is essential in workflow scheduling. Current researches on this topic omitted the fact that, if a workflow net contains selective patterns, then when an instance of which run to a particular time point, it´s possible that some unexecuted activities are bypassed and have no chance to be executed by this instance. Therefore, upper bound of duration of workflow instance must be computed only based on task subnet that consists of executed activities and unexecuted ones that are possible to be executed. In this paper, rules were proposed to build reachable subnets for instances of generalized well-formed workflow, and the complex problem of estimating upper bound of duration for such subnets was decomposed into simpler ones for instance subgraphs. Also, an algorithm to estimating upper bound of duration for workflow instance was proposed and an example was put forward to illustrate the process.