Master the visual language of system interactions. Learn what every arrow, box, and line represents.
Represents a participant (Class, Component, or Actor). The dashed line represents the passage of time downwards.
Indicates that the participant is currently active (executing code). Shows the focus of control.
A blocking call (solid line, filled arrow). Sender waits for response.
A non-blocking call (solid line, open arrow). Sender continues immediately.
Return of control/data to the caller (dashed line, open arrow).
An object calling its own method (loopback arrow).
Repetitive sequence enclosed in a frame labeled 'loop'.
Mutually exclusive choices. Separated by a horizontal divider.
Optional sequence executed only if the guard condition is true.