Fan-out has multiple meanings in software engineering.
In message-oriented middleware solutions, fan-out is a messaging pattern used to model an information exchange that implies the delivery (or spreading) of a message to one or multiple destinations possibly in parallel, and not halting the process that executes the messaging to wait for any response to that message.
[1][2][3] In software construction, the fan-out of a class or method is the number of other classes used by that class or the number of other methods called by that method.
[4] Additionally, fan-out has impact on the quality of a software.
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