A message is defined via a send and receive event, it is used to visualise when an Interaction Partners (UML Sequence) executes some behaviour.
There are several different types of message we need to know about:
Synchronous message (UML Sequence)
Synchronous message: sender waits until it has received a response message before continuing. Syntax is
msg(...parameters).
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Asynchronous message (UML Sequence)
Asynchronous message: sender continues without waiting for a response message. Syntax is
msg(...parameters).
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Response message (UML Sequence)
Response message: may be omitted if the content and location are obvious. Syntax is
attribute = msg(...parameters): return value.
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Found Message (UML Sequence)
Found message: sender of a message is unknown or not relevant.
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Lost Message (UML Sequence)
Lost message: receiver of a message is unknown or not relevant.
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Time-consuming Message (UML Sequence)
Time-consuming message: a message with a set duration. Usually we assume messages are transmitted with no loss of time, we express time elapses between the send and receipt of a message.
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Object Creation (UML Sequence)
Object creation is represented by a dashed arrow with an arrowhead pointing to the head of the lifeline of the object to be created. We use the keyword
new.
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Object Destruction (UML Sequence)
Object destruction is indicated by a large cross at the end of the lifeline.
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