A recent trend in Ubiquitous Computing is that embedded software (e.g. in production machines, wired or wireless networked sensors and actuators, or RFID readers) directly offers Web Services. This allows it to directly participate in IT business processes. Our work suggests an approach to assess and compare the performance of such hybrid process models. It critically evaluates BPEL, the standard instrument for creating executable process descriptions, for its support of the dynamic nature of ubiquitous services, e.g. due to device mobility and unreliable wireless communication. 3