Sending Signal   A sending signal is a representation of an action that sends a signal. The action has one incoming transition and one outgoing transition. The signal is always sent asynchronously; the object receiving the signal may be shown, with a dashed arrow drawn from the pentagon to the object. The signal signature is written inside the pentagon.

Explanation

It is often necessary to notify other objects to signify that particular events have occurred or that a state has changed. This can be represented on an activity diagram with a special symbol whose shape is a pentagon. The pentagon is really an action representing the sending of a signal. The signal is always sent asynchronously, meaning that once the signal is sent the action will allow the transition to the next activity, without waiting for any receipt or acknowledgement from the object or objects to whom the signal was sent.

Related Entries

Receipt Signal  Paired Element,  Graphically Similar A receipt signal is related to a sending signal as a paired element. A classifier sends (asynchronously) a package of information and another classifier receives the information signified by the receipt signal.