Manual for the Beer Game

Manual for the Beer Game

TABLE OF CONTENTS
TABLE OF CONTENTS........................................................................................................2
1. INTRODUCTION................................................................................................................3
2. STARTING THE GAME....................................................................................................4
2.1. DOWNLOADING AND INSTALLING THE GAME .................................................................4
2.2. LOADING THE CPN MODEL.............................................................................................4
2.3. THE USER INTERFACE......................................................................................................7
2.3.1. Current Status.........................................................................................................8
2.3.2. Line Chart...............................................................................................................8
2.3.3. Place Order.............................................................................................................8
2.3.4. Costs until time period............................................................................................8
3. PLAYING THE GAME......................................................................................................9
3.1. FIXED PARAMETERS........................................................................................................9
3.2. PLAYING A SCENARIO .....................................................................................................9
3.3. CUSTOMIZING THE GAME..............................................................................................11
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1. Introduction
The Beer Game is a role-playing simulation developed at MIT in the 1960’s to clarify the
advantages of taking an integrated approach to the managing of a supply chain. Consider a
simplified beer supply chain. This supply chain consists of a retailer, a wholesaler which
supplies the retailer, a distributor which supplies the wholesaler and a factory with unlimited
capacity and raw material which brews the beer and supplies the distributor. Each component
in the supply chain has unlimited storage capacity and there is a fixed supply lead time and
order delay time between each component.
Each week, every component in the supply chain tries to meet the demand of the downstream
component. Any orders which cannot be met or fulfilled are recorded as backorders, and are
met as soon as possible. No orders will be ignored and all orders must eventually be met.
At each period every component in the supply chain is charged a shortage cost of 2 per
backordered item. Also, every period each location is charged inventory holding cost 1 per
inventory item it owns. Each component in the supply chain owns the inventory at that
facility. Assume that the items that are in transit between components have cost zero.
Each supply chain member orders some amount from its upstream supplier. It takes one week
for this order to arrive at the supplier. Once the order arrives, the supplier attempts to fill it
with available inventory, and there is an additional two week transportation delay before the
material being shipped by the supplier arrives at the customer who placed the order.
The goal of the retailer, wholesaler, distributor and factory is to minimize cost. They can
choose to do this individually or for the entire supply chain.
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2. Starting the game
In the next paragraphs you can find how to run and play the game. We start with the installing
of the game. Next we show how to open the CPN model in CPN Tools, and explain the user
interface of the game. The last paragraph will explain the game play in more detail.
To be able to run the game, you need to have installed at least CPN Tools version 1.1.8.
However CPN Tools 1.2.0 is recommended, since it is the most stable version. You will also
need to have at least Java run environment 1.4.1 installed.
2.1. Downloading and installing the game
To install the game, download the beergameall.zip file. Next unzip this file to a folder on your
hard drive. The beergame.cpn file is the CPN model of the Beer Game, the beergame.jar file
is the Java application that belongs to the Beer Game CPN model.
2.2. Loading the CPN model
Loading the CPN model is the same for all of the four games. To load the CPN model for the
game, right click and hold the right mouse button in the workspace. The marking menu as
depicted in figure 1 will appear.
Figure 1
Next move the move cursor to Load Net. Now release the right mouse button. A dialog
window will appear where you can choose a CPN model to load. Here we choose the CPN
model of the Beer Game. Go to the location of the CPN model and choose to open the
beergame.cpn file.
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Figure 2
Now that the CPN model has been loaded, the settings for the simulation toolbox have to be
changed. To do so, click on the triangle next to Tool box, then on the triangle next to
Simulation, and finally on the triangle next to Play. The menu should look like the one
depicted in figure 3. Now change the number of steps of the simulation to a large number, for
instance 100000. The delay in milliseconds has to be set to 1.
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Figure 3
Next left click and hold on Simulation, move the mouse pointer into the work space and then
release it. The simulation toolbox appears. Note that the value beneath the play button should
be equal to the large number, 100000. The simulation toolbox is depicted in figure 4.
Figure 4
To start the simulation, in this the game, left click on the play button. The mouse pointer now
has the play button next to it. Now move the mouse over to the model area as depicted in
figure 5.
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Figure 5
Left click the mouse, and the simulation will start.
!!! IMPORTANT !!!
Before you start the Java application of the game, make sure that the simulation of the game is
started. If this is not the case, then the Java application is not able to connect to CPN Tools.
The application will notify you of this by displaying a message “Could not connect to CPN
Tools…”.
You will have to quit the application and try again.
2.3. The user interface
In the Beer Game Java application you first have to specify the port of CPN Tools to which it
has to connect. By default this is 9000, so you do not have to change anything in the window
as depicted in figure 6.
Figure 6
Before you press the connect button, make sure you have started the simulation in CPN Tools.
If the simulation was started, a window as depicted in figure 7 will appear.
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Figure 7
2.3.1. Current Status
In the current status part you can see the status of the component you are playing. In this case
it is the status of the retailer. Time period is the current period; it is the current time value of
the simulation of the CPN model. Current demand is the demand you are facing for the
current period. Forecast is the demand forecast for the next period. It is based on a moving
average of three periods. The on hand stock is the number of beer cases that the retailer has
available. Still to ship is the customer demand that is not yet fulfilled, whereas still to receive
are the cases of beer you still have to receive from the wholesaler.
2.3.2. Line Chart
The line chart displays the demand and the forecast per time period. The order size line is the
history of orders you have placed.
2.3.3. Place Order
Here you can place order with the retailer. To do so enter a value for your order in the text
field. Make sure you enter an order quantity of 0 or greater. The clear button clears the text
field, whereas the order button places the order at wholesaler.
2.3.4. Costs until time period
Here the holding and backorder costs until the current time period are displayed.
Unfortunately it is not possible to display the costs of the entire supply chain. These have to
be read from the CPN model in CPN Tools
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3. Playing the game
In order to play the game, load the Beer Game CPN model in CPN Tools. This is described in
section 2.2. When you have loaded the model, start the simulation. Now load the Beer Game
Java application and press the connect button. After you have pressed the connect button the
following window should appear:
Figure 8
Refer to section 2.2. if the connection between the Java application and CPN Tools cannot be
established.
Before we explain how to play the game, we first explain the fixed parameters of this game.
3.1. Fixed parameters
Parameter Value
Backorder cost 2
Holding cost 1
Order lead time 1
Supply lead time 2
Table 1
In table 1 the fixed parameters of the Beer Game are listed. In making a decision about the
order size, you have to take into account these values.
3.2. Playing a scenario
If the simulation was started correctly in CPN Tools, a window as in figure 7 will appear. In
the status bar the message “connection established” is displayed, indicating that the
application has a connection with CPN Tools. If the application is not able to connect it will
display this as well. This can happen when for you instance the simulation was not started in
CPN Tools. Assuming that the application was able to connect, you can now start playing the
game.
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The game is played for 23 periods. The goal is to meet customer demand, while minimizing
costs. Since the on hand inventory and the backorders have costs, you have to think about
how much to order every period. The status for a game after 14 periods is depicted in figure 9.
Figure 9
Figure 10
The game ends after 23 periods, this is depicted in figure 10. The status bar also indicates that
the game has ended. To view the costs of the other players in the supply chain you will have
to look in the CPN model.
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3.3. Customizing the game
Some parameters of the game can be changed to be able to try different scenarios. This is
possible because the Java application displays the state of the CPN model. There is no strict
connection between the Java application and the CPN model.
The order and supply lead times can be changed. However these changes require more indept
knowledge of modeling with Petri Nets.
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