The emergence of wireless sensor networks (WSN) and RFID technology are starting to make the ubiquitous computing vision a reality, as they provide the means to obtain information about physical phenomena and entities. However, there is a great need for higher abstraction levels, as the integration of these technologies into current ubiquitous computing systems is still primitive. This problem is addressed by TinySOA, a service-oriented architecture that allows programmers to build their applications by using a simple API provided by language independent Web services. TinySOA contributes to the development of ubiquitous computing applications by facilitating the means to obtain primary context mainly through WSN and RFID. We describe the development of an application using our implementation into a production line scenario.