3.4. Defining the traffic violations DMN decision logic

Procedure

1. To calculate the fine, in the DMN designer canvas, select the Fine decision node and click the Edit icon to open the DMN boxed expression designer.

   図3.10 Decision node edit icon

   

2. Click Select expression Decision Table.

   図3.11 Select Decisiong Table logic type

   
3. For the Violation.Date, Violation.Code, and Violation.Speed Limit parameter fields, right-click and select Delete for each field.
4. Click the Violation.Actual Speed column header and enter the expression Violation.Actual Speed - Violation.Speed Limit in the Expression field.
5. Right-click the Fine parameter field and select either Insert left or Insert right.
6. Click the output-2 column sub-header, enter Amount in the Name field, and select number from the Data Type pull-down menu.
7. Similarly, click the output-1 column sub-header, enter Points in the Name field, and select number from the Data Type field.

8. Next, enter the following values in the first row of the decision table:

   • Violation.Type: "speed"
   • Violation.Actual Speed - Violation.Speed Limit: [10..30)
   • Amount: 500

   • Points: 3

     Right-click the first row and select Insert below to add another row.

9. Enter the following values in the second row of the decision table:

   • Violation.Type: "speed"
   • Violation.Actual Speed - Violation.Speed Limit: >= 30
   • Amount: 1000

   • Points: 7

     Right-click the second row and select Insert below to add another row.

10. Enter the following values in the third row of the decision table:

    • Violation.Type: "parking"
    • Violation.Actual Speed - Violation.Speed Limit: -
    • Amount: 100

    • Points: 1

      Right-click the third row and select Insert below to add another row.

11. Enter the following values in the fourth row of the decision table:

    • Violation.Type: "driving under the influence"
    • Violation.Actual Speed - Violation.Speed Limit: -
    • Amount: 1000
    • Points: 5
12. Click Save.
13. To define the driver suspension rule, return to the DMN designer canvas, select the Should the driver be suspended? decision node, and click the Edit icon to open the DMN boxed expression designer.
14. Click Select expression Context.
15. Click ContextEntry-1, enter Total Points as the Name, and select number from the Data Type pull-down menu.
16. Click the cell next to Total Points, select Literal expression from the context menu, and enter Driver.Points + Fine.Points as the expression.
17. In the cell below Driver.Points + Fine.Points, select Literal Expression from the context menu, and enter if Total Points >= 20 then "Yes" else "No".

18. Click Save.

    You have defined how to calculate the fine and the context for deciding when to suspend the driver. You can navigate to the traffic-violation project page and click Build to build the example project and address any errors noted in the Alerts panel.