FTS is two things:
1. An engine to enable event-flow programming
2. A decomposition pattern to turn conventional components into event-flow components
Event-Flow is an architectural style that combines flow-based programming (FBP) and event-based systems (EBS). From FBP, it takes the notion that a program is composed from independent processing nodes ("functions", if you will) that take inputs and produce outputs. From EBS, it takes the idea that the connections between components are defined outside of the components, i.e. components do not send messages to each other but leave that to the engine.