What makes workflows work in an opportunistic environment?

In this paper, we examine the issues of workflow mapping and execution in opportunistic environments such as the Grid. As applications become ever more complex, the process of choosing the appropriate resources and successfully executing the application components becomes ever more difficult. This may include extension or reduction of the initial workflow mapping as necessary for the actual execution. In this paper, we focus on the interplay between a workflow-mapping component that plans the high-level resource assignments and the workflow executor that oversees the component execution. We concentrate particularly on issues of data management and we draw from the experiences with mapping and execution systems: Pegasus, DAGMan and Stork.