What is Context diagrams ?

Definition

A context diagram is a simple graph where nodes represent system components and edges represent connections through shared phenomena declared by the labels (DeMarco, 1978; Jackson, 2001).

For example

The Initiator component controls the meetingRequest event, whereas the Scheduler component monitors it; the Scheduler component controls the constraintsRequest event, whereas the Participant component controls the constraintsSent event.

A component in general does not interact with all other components. A context diagram provides a simple visualization of the direct environment of each component; that is, the set of 'neighbour' components with which it interacts, together with their respective interfaces.