By nature, ubiquitous computing applications are intimately intertwined with users' everyday life. This situation is challenging because it requires to make the development of applications accessible to end-users. Furthermore, ubiquitous computing consists of a variety of areas, including home automation and assisted living, raising a need for an open-ended approach. We present Pantagruel, a visual programming language that is end-user oriented. Our approach is open-ended in that Pantagruel integrates a language to describe a ubiquitous computing environment in the form of a taxonomy, defining the entities relevant to a given ubiquitous computing area. This description serves as a parameter to a sensor-controller-actuator development paradigm. The orchestration of area-specific entities is supported by high-level constructs, customized with respect to taxonomical information.