Car Repair Process

Artifact and Package

1. Open the Configure BPSim window ('Simulate > Process Analysis > BPSim > Open BPSim Manager').
2. Create a Business Process Simulation Artifact named Scenario 1: Main flow.
3. Select the Package containing the corresponding BPMN 2.0 model.

Start and Duration

We will simulate the processes in a car repair shop whose opening hours are from 9:00 am to 5:00 pm, which is a period of 8 hours. We also suppose that a customer walking in after 4:50 pm will not be served on that day. Therefore the simulation Start time is 9:00 am and the duration is 7 hours and 50 minutes.

On the 'Car Repair' diagram, click on the Business Process Simulation Artifact named Scenario 1: Main Flow and, on the Configure BPSim window, update these ScenarioParameters:

• Start - overtype the 'Values' field with any date (in the format dd/mm/yyyy) and change the time section to '9:00 AM'

• Duration - click on the button in the 'Values' field and set it to a Constant Duration of '0 07:50:00'

Customer Arrives

We will simulate a customer arriving every 24 minutes.

The first customer arrives at 9:00 AM and the last arrives at 4:36 PM (the customer arriving at 5:00 PM will not be served today because that is constrained by the 'Duration' setting).

With a pen and paper, we can calculate that there are 20 customers served (9:00 AM to 4:36 PM = 456 minutes; number of customers is 456/24 + 1 = 19 + 1 = 20). We will verify this with the simulation result later.

On the 'Car Repair' diagram, click on the Start Event element Customer Arrives, and in the Configure BPSim window:

1. Click on the New Parameter drop-down arrow, and select 'Control'.
2. Click on the 'Parameter' drop-down arrow and select 'InterTriggerTimer'.
3. In the 'Values' field click on the button and set a Constant Numeric value of '24 minutes'. Click on the OK button and the Save toolbar icon.

Property Parameters

We suppose each customer's car might initially have a different number of issues. This could be reflected using a random number generator. BPSim provides a number of distributions to suit your needs.

In this example, we use a Truncated Normal distribution to initialize the property noOfIssues. Tasks Repair Issue and Handle New Found Issue will decrement and increment the value of noOfIssues respectively.

1. On the 'Car Repair' diagram, click on the Start Event Customer Arrives.
2. On the 'Configure' tab of the Configure BPSim window, click on the New Parameter drop-down arrow and create a Property parameter called noOfIssues.
3. In the 'Values' field click on the button; the 'Configure 'noOfIssues' for 'CustomerArrives'' dialog displays.
4. Click on the 'Distribution' tab and select 'TruncatedNormal'; in the fields:
        -  'Mean', type '2'
        -  'StandardDeviation', type '1'
        -  'Min', type '1'
        -  'Max', type '1000'

Important Note: Distributions such as 'TruncatedNormal', return a floating point value, but the property is used as an integer. Setting the property's type is important, especially in condition expressions when testing with equality. For example, the condition expression getProperty('noOfIssues') = 0 will almost never be satisfied because noOfIssues was initialized by a floating point distribution.

Tip: How to customize the type for a property

After you create the property and set a value, click on the icon on the toolbar, and then click on the icon to display the 'Edit Property Parameters' dialog. In the 'Type' field for the property, click on the drop-down arrow and select the value 'int' instead of the default 'double'.

1. On the 'Repair Car' diagram, click on the Activity Repair Issue.
2. On the 'Configure' tab of the Configure BPSim window, click on the New Parameter drop-down arrow and create a Property parameter called noOfIssues.
3. In the 'Values' field click on the button. The 'Configure 'noOfIssues' for 'Repair Issue'' dialog displays.
4. Click on the 'Expression' tab and, in the 'Expression' field, type {noOfIssues} -1; click on the OK button.
5. On the 'Repair Car' diagram, click on the Activity Handle New Found Issue.
6. On the 'Configure' tab of the Configure BPSim window, click on the New Parameter drop-down arrow and create a Property parameter called noOfIssues.
7. In the 'Values' field click on the button. The 'Configure 'noOfIssues' for 'Handle New Found Issue'' dialog displays.
8. Click on the 'Expression' tab and, in the 'Expression' field, type {noOfIssues} +1; click on the OK button.

Probability on Sequence Flows

We estimate that one in three of the customers will not accept the initial estimate for repairs and the remaining two will accept it. We also estimate that for one in four of the repairs new issues will be found, and for the remaining three repairs no new issues will be found.

On the 'Car Repair' diagram, refer to the Gateway element Accepted?. Click on the:

• Initial Estimate Accepted Sequence Flow and in the Configure BPSim window click on the New Parameter drop-down arrow, and create a Control parameter called 'Probability'; in the 'Values' field type '0.67'
• Initial Estimate Not Accepted Sequence Flow, and in the Configure BPSim window click on the New Parameter drop-down arrow, and create a Control parameter called 'Probability'; in the 'Values' field type '0.33'

On the 'Car Repair' diagram, refer to the Gateway element New Issue Found?. Click on the:

• No More Issues to Repair Sequence Flow and in the Configure BPSim window click on the New Parameter drop-down arrow, and create a Control parameter called 'Probability'; in the 'Values' field type '0.75'
• More Issues to Repair Sequence Flow and in the Configure BPSim window click on the New Parameter drop-down arrow, and create a Control parameter called 'Probability'; in the 'Values' field type '0.25'

Condition on Sequence flows

We use an expression to return a Boolean value as a Sequence Flow's condition, which plays a key role in the flow's logic.

On the 'Repair Car' diagram, refer to the Have Further Issues? Gateway element. Click on the:

• More Issues to Repair Sequence Flow and in the Configure BPSim window click on the New Parameter drop-down arrow, and create a Control parameter called 'Condition'; in the 'Values' field click on the button, click on the 'Expression' tab and type {noOfIssues} != 0 in the 'Expression' field
• No More Issues to Repair Sequence Flow and in the Configure BPSim window click on the New Parameter drop-down arrow, and create a Control parameter called 'Condition'; in the 'Values' field click on the button, click on the 'Expression' tab and type {noOfIssues} = 0 in the 'Expression' field

Note: All the outgoing transitions from a Gateway should include 100% of the logic; for example, you would not enter {noOfIssues} > 10 and {noOfIssues} < 5 as condition expressions, because values in the range [5, 10] will not be handled by any outgoing Sequence Flows.