In this paper, we present the Deployment Support Network (DSN), a new methodology for developing and testing wireless sensor networks (WSN) in a realistic environment. With an additional wireless backbone network a deployed WSN can be observed, controlled, and reprogrammed completely over the air. The DSN provides visibility and control in a similar way as existing emulation testbeds, but overcomes the limitations of wired infrastructures. As a result, development and experiments can be conducted with realistic in- and outdoor deployments. The paper describes the new concept and methodology. Additionally, an architecture-independent implementation of the toolkit is presented, which has been used in an industrial case-study.