The Reactor architectural pattern demultiplexes and dispatches requests that are delivered concurrently to an application by one or more clients. 

Reactor is one of the patterns documented at:
http://www.cs.wustl.edu/~schmidt/patterns/patterns.html
''however, it's not easy to see '''where''' there-in it's documented. How about a quick summary for those of us unwilling to mine the WUStl page?''

The reactor pattern itself is documentent in "Patterns for Concurrent and Networked Objects, Volume 2". The above top-level link is still relevant because the reactor pattern can't easily be considered in isolation (especially in isolation of the other Event Handling Patterns http://www.cs.wustl.edu/~schmidt/POSA/POSA2/event-patterns.html)
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Is there a relationship to ReactiveProgramming?
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CategoryPattern