We present a language of temporal conditions for detecting concurrent events in embedded Web-enabled devices, and for triggering pervasive services on these systems. Based on the assumption that evaluating conditions on distributed devices is relevant for providing robustness and to foster scalability and web real-time, we discuss the feasibility of in-situ evaluation of the proposed conditions and conduct a performance study. In a smart environments use case, it is illustrated how the language can be used to state activation concerns of services on distributed Web resources. Our proposed architecture integrates the language with the Web of Things to foster simplified development of applications that mash up Web-enabled devices.