Abstract. Control systems for electrical microgrids rely ever more on heterogeneous off-the-shelf technology for hardware, software and networking among the intelligent electronic devices that are associated with dispersed energy resources. For distributed microgrid applications in a dynamic environment, overlay networks provide an opportunity for a flexible and robust logical communication infrastructure among these intelligent electronic devices. Agora is a semantic overlay network that allows to efficiently route queries -related to microgrid control- in the overlay network, based on an XML description of the static and dynamic characteristics of the intelligent electronic devices. It is robust against changes in the microgrid and ICT infrastructure, and provides graceful degradation in case of unrecovered failures. 1 Motivating a Flexible, Dependable Information Infrastructure More and more small-scale dispersed energy resources (DERs) (e.g. wind turbines, photovoltaic panels, coup...