Software-defined networking (SDN) is a new approach to designing networks. SDN decouples and migrates network control from the hardware, which enables innovative and efficient network design and operation. The SDN-based design is well adopted in data centers and enterprises. In this paper, we state that SDN-based design is beneficial in the multihop wireless networks like wireless sensor network (WSN) and propose an architecture called SDSense. We propose a novel principled approach of SDN-based WSN design, where we decompose network functions as slow (e.g., topology control) and fast (e.g., congestion control) changing components. Furthermore, we derive a network utility maximization framework for better resource allocation. We implement SDNSense, where software enabled sensors are dynamically reconfigured to adapt to current network conditions and demonstrate that SDSense can significantly improve the network performance compared to its counterparts.