Using Blackboards to Optimize Grid Workflows with Respect to Quality Constraints

Composing grid services to workflows, which solve specific problems is not a trivial task. Various parameters like for example timing constraints, desired quality of solution, availability of (computing) resources, error recovery, payment and security issues, to name only a few, have to be considered. The heterogeneity and the highly dynamic nature of the grid pose additional challenges. Current implementations try to construct workflows based on the user´s needs and the capabilities of the respective services before the actual run. In this paper we propose a blackboard method that is able to find (near) optimal workflows and accommodate to changing conditions like for instance delays or faults on the fly