In this paper, we present a novel named data aggregation method dedicated to wireless sensor networks. The method relies on an adaptation of the CCNx protocol implementation that we have extended with in-network processing functions to aggregate named data efficiently. We have implemented and tested our solution with the Contiki operating system which is an operating system for resources-constrained embedded systems and wireless sensor networks. Our simulation and measurement results using the Cooja simulator and physical nodes show that our solution has a small overhead in terms of exchanged messages and provides acceptable data retrieval delays.