Queues
A Queue is a place where work to be done can wait until appropriate Resources or Activities are available.
A Queue is one of the fundamental objects that make up the structure of your simulation.
For purposes of animation, Queues are assumed to be “close to” the Activities they feed. This means the Work Items take no time to travel from a Queue to an Activity. However, Work Items may, take time to travel from an Activity to a Queue.
Work Items can be allowed to “expire” while in a Queue. For example if people enter a shop and are willing to Queue for up to 5 minutes, set the Shelf Life in the Queue dialog to 5 minutes.
When simulating some processes (e.g. an oven) you might want to use a Queue to act as a simple Activity but one that can contain many Work Items. However you would want to set a minimum time that the Work Items must stay in the Queue. Use the Min Wait Time box to set this minimum.
Queue Options
The Queue's contextual tab can be used to define the settings for a Queue.
To change the name of a Queue, type a new title in the Name box in this menu.
If the Queue has limited Capacity (for example it is a mechanical buffer), type the maximum number of items into the Capacity box.
If items should not stay in this Queue for more than a limited time, populate the Shelf Life box with the time limit (in simulation time units).
To make Work Items wait for at least a certain time in the Queue use the Min Wait Time field.
If you want the simulation run to start with items already in this Queue then click the START-UP button.
The Current Contents dialog lets you see the details of the Work Items that are currently in this Queue.
Normally Work Items join the back of a Queue and do not leave until they reach the front. Exceptions are:
- Items whose shelf life has expired and are removed by an “expired only” Activity.
- Items that do not join the back of the Queue because they have been prioritized.
Some of the results information for Queues can be segregated by a Label to let you see how long different types of work spend in the Queue.
On the Queue’s Additional tab, you can find and adjust more of the Queue’s Properties.
The Graphics tab lets you redefine how the Queue appears on the screen (including showing an animated Queue).
You can access all properties of a Queue by double-clicking on it.
