BPMS

How to Create Business Rule Tasks in jBPM

Business Rule Tasks help us run complex logic within our workflows. Leave those if-statements behind!

TiOluwa Olarewaju

Nov 27, 2019 • 4 min read

You’re creating business processes for your company using JBPM.

But some of your workflows contain complex logic: regulatory rules, pricing conditions, and approval criteria.

And if you try to write a thousand if-statements, it'll be a nightmare to change any one of them.

So what do you do?

Use Business Rule Tasks

Business rule tasks help us run complex logic within our business process. These tasks make external calls to our rules engine, so our processes remain tidy and easy to change.

Create a Business Process

What You’ll Need

JBoss Developer Studio w/ JBoss EAP 7.1+ Download here
JBoss Maven Repositories (Section 1: Steps 4-7)
Red Hat Process and Rules Development Stack (here)
Basic Maven & BPM knowledge

We’ll create a fictitious credit card approval process. During the process, we'll check certain credit score and income conditions to see whether a candidate will be approved.

Create a Business Task

Step 1: Download and import simple-rule-process-starter

Step 2: Review the CreditApplication object (src/main/java/CreditApplication)

This object will hold our credit application. Objects that are inserted into the rule engine are called facts.

Step 3: Review the business process (src/main/resources/com/sample/sample.bpmn)

Review the Credit Application Process

Review the creditApplication variable - We’ll use this to store our application
Right click anywhere in the process → Show property view → Data Items

Script Tasks - Here we setup our credit application and print out the approval status
Double click the first and last task in the process

Step 4: Add a business rule task

Mouse over the script task called “CHANGE ME”. Click the lighting rod and select Business Rule Task
Open the Business Rule Task
Set the rule-flow-group to credit-approval. A ruleflow-group tells our engine which rules to run

Under IO params tab, set the input data mapping. We're passing in our creditApplication variable into the rules engine.

Set the output data mapping. After the rules fire, this will map the output of the rule execution back to our process variable.

Under the General tab, change the name to “Credit Approval”

Step 5: Save the file

Create a Business Rule

Step 1: Open the drl file - (src/main/resources/com/sample/rule.drl)

Drools Rules Language is one language we write rules in
You can also create your rules using an excel file

Step 2: Write the rule package com.sample

package com.sample
import org.codelikethewind.facts.CreditApplication;

rule "Credit Approval"
ruleflow-group "credit-approval"
no-loop

    when
        $creditApplication : CreditApplication( creditScore > 500, annualIncome > 50000 )
        then
            $creditApplication.setApproved(true);
            update($creditApplication);
end

Our rule consists of a few things

rule name → “Credit Approval”
rule-flow-group → a way to tell engine what rules to run
no-loop → tell engine to not re-execute this rule
when → condition of our rule
then → the action to take

This rule happens to be quite simple. But you can expand this system to execute any number of complex rules.

Step 3: Build the project

mvn clean install

Run the Process

Step 1: Deploy the simple-embedded-rule-process to your server

Download the project & run mvn clean install
This simple project runs a deployed process.
Deploy using Method 1 here. If you’re on EAP 7, be sure to start your server with the full profile:./standalone.sh --server-config=standalone-full.xml

Step 2: Run the Process

Go to http://localhost:8080/simple-embedded-process/
Click “Start Process”

Step 3: Verify the rule

Check the logs. You should see “Credit Application Approved”

Recap

Well Done! Let's review what we just did.

We’ve created a business process for our fictitious credit application
We used a business rule task to decide whether we’ll approve a candidate.
We created a rule that contains logic for our approval. Rules are in “when this, then that” form.

Business rule tasks are a great way to run complex logic in your workflows. They make it easy to change the rules independently of your process.

Source Code & Useful Links

Happy Coding!

-T.O