Messages on input ports when needed. Behaviours run in parallel. There is no central model of the world. There is no separation into perception, central processing, and actuation systems. They are intertwined.
Messages are available on the appropriate input port when needed.
There s no notion of synchronisation between a producer and consumer. Message reception buffers can be overwritten by new messages before consumer has looked at old one. Behaviours run in parallel, requiring conflict resolution when different behaviours attempt to control the same actuator in different ways. This is done via a pre-wired priority scheme.