Ubiquitous computing environments are becoming the convergence of a variety of devices and technologies. The environments consist of a group of independently executing devices which have complicated functions on heterogeneous platforms. In this paper, a service-oriented architecture is presented to implement ubiquitous computing environments in which complex events occur from various sensors, communication devices, and web service providers. It is assumed that web services technologies will be more spread among the heterogeneous device platforms over the internet protocol.