The first part of this chapter, as summarized in the foregoing paragraphs, presents the architecture of Mac OS X as layers of system software. Following this static perspective of Mac OS X is a more dynamic view that traces the progress of a user event through the system. A typical event in Mac OS X originates when the user manipulates an input device such as a mouse or a keyboard. The window server dispatches the event to the appropriate run-loop port of the target process. There the event is picked up by the Carbon Event Manager and forwarded to the event-handling mechanism appropriate to the application environment.
Events can also be asynchronous, such as a network packet containing configuration changes.