Recently, the research trend and developmental tendency of ubiquitous computing technologies have been heading in the direction which seamlessly provides the optimum service to users through context-awareness, analogy and networking with various sensor nodes. There is an overwhelming need to develop the USN middleware platforms that have the functions for processing data, monitoring, merged communication environments and mutual compatibility with a variety of sensor networks. While research on a base technique in regard to hardware and communication of sensor networks is actively advancing, the middleware technique is still in the early stages. This paper identifies some drawbacks in the previous work. USN middleware was proposed to control application services through context-awareness processing, information collection from sensor networks and design of event-centric architecture.