tut02 - Basic Queue-Server Model

• Example tut02:
  • basic queuing system
    • entities are simply numbers ("id's")
  • model
    • 
  • components
    • am_generator outputs increasing integer values in fixed time intervals
    • am_queue stores them, using a FIFO discipline
    • am_expserver processes one entity at a time with exponentially distributed service times
    • am_terminator terminates incoming entities
    • 3x am_toworkspace collect output values of generator, queue and server
  • am_expserver uses seed for reproducible results
  • result
    • 
• Solution of timing problems:
  • model is similar to example singleserver
  • difficult timing
    • server sends working = true to queue input bl
    • → queue sets internal state isBlocked = true
    • must be ready, before another entity leaves the queue
  • doesn't work in RPDEVS
  • solution in NSA-DEVS
    • am_queue has default value tD = [0, 2] ≙ 2 ε
    • → queue is blocked, before another entity can leave