Sequence Diagram Messages
A Sequence diagram's main purpose is to show the ordering, sending
and receiving of messages among a family of objects. In a sequence diagram
there are essentially three basic types of messages:
Figure 1 - Message types
- Synchronous messages - Messages that the controlling object waits for
the recipient to resolve and return status. These messages are notated by
a solid line with an arrow head
- Asynchronous messages - Messages that are essentially fire and forget.
The sender does not wait for resolution or status of the results of the message.
These messages are represented by a solid with an half-arrow head.
- Return value - messages that are the response of another message. These
can be either synchronous or asynchronous and are depicted by a dashed line
with an appropriate arrowhead for synch or asynch.