Workflow management in large-scale Grid environments is a very challenging task centralized management systems are not able to cover sufficiently. Therefore, we present our Workflow On-line Resource Management (WORM) architecture built on top of active network technology. The approach integrates a peer-to-peer like organized workflow management system with existing or newly built management systems for the resources building the Grid. In our approach, each workflow is represented by a mobile autonomous entity which uses the active network infrastructure to move through the Grid, which is represented by an active overlay network on top of existing network infrastructure. Thus, control of the workflow execution is handed over to the autonomous code without requiring a central system to be in charge of the computation and cope with reservation, failures, etc. The WORM architecture is presented together with a classification into the taxonomy of workflow management systems.