Unified Modeling Language Reference Manual, The, Second Edition

signal

The specification of a block of information to be communicated asynchronously between objects. Signals have parameters expressed as attributes.

See also event, message, send.

Semantics

A signal is an explicit named classifier intended for explicit communication between objects. It has attributes that constitute its information. It is explicitly sent by an object to another object by a send action. A broadcast action sends a signal to the set of all objects—although, in practice, it would be implemented differently for efficiency. The sender specifies the attributes of the signal at the time it is sent, either as an argument list or by supplying a signal object whose attributes have already been initialized. Once a signal has been sent, ...