Methods, systems, and apparatus, for defining and monitoring an event for a physical entity and the performance of an action in response to the occurrence of the event. A method includes receiving data indicating an event for a physical entity, the event specified in part by a physical environment feature for which the occurrence of the event is to be monitored by the data processing apparatus; receiving data indicating an action associated with the event and to be taken in response to the occurrence of the event; monitoring for the occurrence of the event for the physical entity; and in response to the occurrence of the event, causing the action associated with the event to be performed.