Recently, middleware has started playing an important role in embedded devices and applications. The recent advances in wireless communication and micro system technology have evolved the construction of sensor networks for sensing environmental parameters, processors, wireless communication capabilities, and autonomous power supplies in tiny devices in large quantities at low cost. Large and dense networks of these devices can then be deployed discreetly in the physical environment in order to observe a wide variety of real-world phenomena. With the continuous growth of sensor networks, monitoring has become an important problem. In this paper, we present a middleware service for monitoring sensor networks and applications with an illustrative example.