Creating Your First Decision Table¶

This guide walks you through creating a decision table for a simple shipping charges calculation system. You'll build the same shipping charges example mentioned in the documentation, but with a step-by-step approach.

Example Use Case: Shipping Charges¶

Our online shopping platform has the following shipping pricing rules:

Free shipping when:
The order has 4+ items AND the total is $300+
Standard shipping is selected (4-5 business days)
Otherwise, shipping charges vary based on:
Number of items
Delivery speed (Next day, 2^nd day, or Standard)
Order total (less than $300 or $300+)

Step 1: Create a New Excel Spreadsheet¶

Open Microsoft Excel® or your preferred spreadsheet application
Create a new blank workbook
Save it as ShippingCharges.drl.xlsx in your project's src/main/resources/rules directory.

Important: Starting with Drools v8, file extension must end in either .drl.xls, .drl.xlsx, or .drl.csv

Step 2: Define the RuleSet Area¶

The RuleSet area defines global elements for all rules in the package.

In cell A1, type a descriptive comment like Shipping Charges Decision Table
In cell B1, type RuleSet
In cell C1, type com.example.shipping (this will be your rule package name)
Move to the next row (row 2)
In cell B2, type Import
In cell C2, type com.example.model.Order, com.example.model.Charge

Your worksheet should now look like this:

A	B	C
Shipping Charges Decision Table	RuleSet	com.example.shipping
	Import	com.example.model.Order, com.example.model.Charge

Step 3: Define the First RuleTable¶

Now let's create the rule table for orders under $300:

Skip a row and in cell B4, type RuleTable followed by a name: RuleTable Shipping Under 300
In row 5, define the condition and action headers:
Cell B5: CONDITION
Cell C5: CONDITION
Cell D5: ACTION
In row 6, define the object types:
Cell B6: $order : Order
Cell C6: Order
Cell D6: (leave empty)
In row 7, define the constraints and actions:
Cell B7: total < 300
Cell C7: itemsCount == $1, deliverInDays == $2
Cell D7: insert(new Charge($param));
In row 8, add descriptive column headers:
Cell B8: Under $300
Cell C8: Items & Delivery
Cell D8: Shipping Charge

Now add your rule data rows (rules 9-14):

A	C	D
9	3 or fewer, 1	35
10	3 or fewer, 2	15
11	3 or fewer, 3-5	10
12	4 or more, 1	N*7.50
13	4 or more, 2	N*3.50
14	4 or more, 3-5	N*2.50

B	C	D
RuleTable Shipping Under 300
CONDITION	CONDITION	ACTION
$order : /orders	$order : /orders
total < 300	itemsCount $1, deliverInDays == $2	charges.add(new Charge($param));
Under $300	Items & Delivery	Shipping Charge
	< 3, 1	35
	< 3, 2	15
	< 3, 5	10
	>= 4, 1	$order.getItemsCount() * 7.50
	>= 4, 2	$order.getItemsCount() * 3.50
	>= 4, 5	$order.getItemsCount() * 2.50

Step 4: Create the Second RuleTable¶

Now let's add rules for orders of $300 or more:

Skip a row after the previous table
In cell B16, type RuleTable Shipping Over 300
Repeat the same headers and descriptive rows as with the first table
Change B19 (the constraint) to total >= 300
Use the same format for the other condition and action cells

Add the data rows for orders of $300 or more:

A	C	D
21	3 or fewer, 1	25
22	3 or fewer, 2	10
23	3 or fewer, 3-5	N*1.50
24	4 or more, 1	N*5
25	4 or more, 2	N*2
26	4 or more, 3-5	0

Step 5: Create the Data Models¶

Now, let's create the Java classes that represent our data model:

Order.java¶

package com.example.model;

public class Order {
    private int itemsCount;
    private double total;
    private int deliverInDays;

    public Order() {
    }

    public Order(int itemsCount, double total, int deliverInDays) {
        this.itemsCount = itemsCount;
        this.total = total;
        this.deliverInDays = deliverInDays;
    }

    public int getItemsCount() {
        return itemsCount;
    }

    public void setItemsCount(int itemsCount) {
        this.itemsCount = itemsCount;
    }

    public double getTotal() {
        return total;
    }

    public void setTotal(double total) {
        this.total = total;
    }

    public int getDeliverInDays() {
        return deliverInDays;
    }

    public void setDeliverInDays(int deliverInDays) {
        this.deliverInDays = deliverInDays;
    }
}

Charge.java¶

package com.example.model;

public class Charge {
    private double amount;

    public Charge() {
    }

    public Charge(double amount) {
        this.amount = amount;
    }

    public double getAmount() {
        return amount;
    }

    public void setAmount(double amount) {
        this.amount = amount;
    }

    @Override
    public String toString() {
        return "Shipping charge: $" + amount;
    }
}

Complete Example¶

Your completed decision table should look like this:

In the next section, we'll show you how to run this decision table with a simple Java application.

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