Model for Queue statistics

This section covers the queues' statistics.

Queues are used to represent specific model dynamics, in which an entity has to wait for another entity.

A pictorial example would be:

• Imagine the daily operation of a barber shop.
• There are two barbers that are being entered into the waiting Barber-Queue at the beginning.
• In the morning there are no customers, the barbers are just sitting around and waiting (in the queue).
• Suddenly at 10 O'clock the first customer arrives and inserts himself into the customer-queue.
• Since there are no other customers, this customer gets removed from the queue instantly along with a barber from the barber-queue.
• Ten minutes later two additional customers enter the barber shop and the customer-queue.
• There is only one barber available, so the first customer from the customer-queue gets served.
• The other one must remain in the queue until one of the barbers is available again.
• This goes on until the shop closes.

Our queue statistics get updated every time an entity enters or leaves a queue. See the following model and its report for a detailed example.

The Model

Process description

• The "Controlling" process starts constantly each hour.
• It contains one activity that lasts between one and two hours.
• Additionally the activity sends a message to the "Marketing" process and terminates after that.
• Note that messages are sent once the activity has been reached.
• The Marketing process is as trivial as the one mentioned before.
• However, we constructed its simulation parameters in a way, so that we get significant queue-statistics in any case.
• To achieve this, we made the "Marketing" process start every two hours (Constant Distribution).
• Thus, the "Controlling" process always sends a message to the bottom pool's activity, before any process instance can reach it.
• This means the message is being queued to be handled by a to-be process instance, that starts in the future (simulation time).

See the report for the description of the resulting queue statistics.