This paper suggests smart gateway structure and functionalities that provide device web service which can be used by user using objectified devices. The smart gateway objectify a physical device in other to provide the device web service in IoT intelligent service. And the paper suggests a mechanism that provide orchestrated service of various devices to user using a concept of service overlay network. and also suggests a interface that provide device web services and the orchestrated service between the smart gateway and a web service platform. In the paper, the objectified devices can be combined with web service objects and device contexts based on the service overlay network, furthermore the objectified devices can provide intelligence and dynamic service in the IoT environment.