Queuing theory:
• Queuing theory deals with the analysis of lines where customers wait to receive a service:
– Waiting at Quiznos
– Waiting to check-in at an airport
– Kept on hold at a call center
– Streaming video over the net
– Requesting a web service
• A queue is formed when request for services outpace the ability of the server(s) to service them immediately
– Requests arrive faster than they can be processed (unstable queue)
– Requests do not arrive faster than they can be processed but their processing is delayed by some time (stable queue)
• Queues exist because infinite capacity is infinitely expensive and excessive capacity is excessively expensive Queuing Theory Hall of Fame: Erlang, Kendall, Little, Jackson, Buzen, Denning.