Abstract: High-order events may be generated and consumed in a cascading computing model. Low level information, such as changes in physical sensor readings, may be communicated to an application in the form of event messages that are generated by an operating system service. In one example, models that implement high level abstractions may also use events to communicate facts that have been inferred from lower level facts. For example, a program might generate events indicating that a particular type of motion (e.g., walking) has started or stopped, where the program infers the walking motion from sensor data about acceleration and position. Another program could consume those events and other data to draw higher level conclusions, such as “Joe is walking to a meeting”. Thus, events may be used in a cascading model in which events are generated and consumed at increasingly high levels of abstraction.