Grid Workflow Optimization Regarding Dynamically Changing Resources and Conditions

Automatic construction of workflows on the Grid currently is a hot research topic. The problems that have to be solved are manifold: How can existing services be integrated into a workflow, that is able to accomplish a specific task? How can an optimal workflow be constructed in respect to changing resource characteristics during the optimization process? How to cope with dynamically changing or incomplete knowledge of the goal function of the optimization process? - and finally: How to react to service failures during workflow execution? In this paper we propose a method to optimize a workflow based on a heuristic A * approach that allows to react to dynamics in the environment, as changes in the Grid infrastructure and in the users requirements during the optimization process and failing resources during execution.