Integrating DROOLS With Mule ESB

1. Integrating DROOLS With Mule ESB
JITENDRA BAFNA

2. Integrating DROOLS With Mule ESB
Overview
DROOLS is Business Logic integration platform (BLiP). It is written in Java. It is an
open source that is backed by RedHat and JBoss. It is Business Rules Management
System (BRMS) solution. It provides a core Business Rules Engine (BRE), a web
authoring and rules management application (Drools Workbench) and an Eclipse
IDE plugin for core development. It is one of the best open source rule engine
provides Complex Event Processing.
Facts are stored in working memory (like in-memory database), Fact is piece of
data, such as salary=3000 or in object oriented rules engine, it may be java object
with properties.
Rules are defined in a knowledge base.A rule consists of conditions (which
typically depend on facts in the working memory) and actions which are executed
when the conditions are true (similar to an "if-then" statement).

3. Integrating DROOLS With Mule ESB
Advantages Of DROOLS Rules Engine
• Reusability: The rules are kept at some centralized location (separation of business logic from
rest of system), it is easy to reuse Drools rules engine.
• Flexibility: Changing the application or its model is not easy task but it is very easy to change the
rules than Java code.
• Redeploying: It is easy to redeploy modified rules without stopping or modifying the application
logic.
• Easier To Understand: It is easier to understand the rules for new developers that code written in
java or any other languages.
• You can avoid lot of if-else from your actual business logic by separating or implementing
business rules separately.
• Unifying: The Drools platform brings unification of rules and processes. It is easy to call rules
from a process or vice versa.
• Easy to implement Complex logic using Drools Rules Engine.

4. Integrating DROOLS With Mule ESB
Considerations for Using Drools Rule Engine
• Let consider that DROOLS should be used when your Business Logic is very
complex. Apart from complex business logic, you can use Drools in below
situations
• Application business logic often change.
• Business Logic contains lot of If-Else statements.
• The business logic is overly complex or time-consuming when defined
procedurally.
• The business logic needs to be maintained by people who don’t (or shouldn’t)
have access to the application itself (to recompile/redeploy it).
• Domain experts (or business analysts) are readily available, but are nontechnical.

5. Integrating DROOLS With Mule ESB
BusinessUseCase
Todaywe will goingto implementbusinessuse case such as Life insurance
policy,dependingon age and policytype,we will be providingpremium amount.Below is
the logicsfor our businesscases
• If age < 10 and policyType= "Policy1",then premiumAmount= 20000.
• If age is between 10 and 40 and policyType= "Policy1", then premiumAmount= 30000.
• If age > 40 and policyType= "Policy1", then premiumAmount= 40000.
• If age < 10 and policyType= "Policy2",then premiumAmount =21000.
• If age is between 10 and 40 and policyType= "Policy2", then premiumAmount =32000.
• If age > 40 and policyType= "Policy2", then premiumAmount= 43000.
Our flow willreceive belowJSON messageand we will use JSON data to pass throughour
rules engine.

6. Integrating DROOLS With Mule ESB
Once JSON message passed through Rules Engine and our expected output is
shown below.

7. Integrating DROOLS With Mule ESB
Implementing DROOLS With Mule ESB
Now, we will walkthrough how to integrate the Mule ESB and Java rules engine
namely DROOLS.
Create Mule project and named the project droolsexample.xml and you can select
Mule runtime 3.6 or higher.
NamespaceAnd Schema
First thing we need to add namespace and schema location to mule configuration
file (e.g. droolsexample.xml).

8. Integrating DROOLS With Mule ESB
Initialize BPM Rules
Add below tag in droolsdemo.xml and it will tell the mule flow there is some rules
defined in your flow and it will start DROOL's working memory.
Defining Mule Flow With DROOLS Rules
We will be receiving the JSON message and it will be converted into Java object
using JSONTo Object transformer. Our Java class for Insurance will look like this:

9. Integrating DROOLS With Mule ESB
package com.drools.example;
publicclass Insurance {
private String name;
private int age;
private String policyType;
private int premiumAmount;
publicString getName()
{
return name;
}
publicvoid setName(String name)
{
this.name=name;
}
publicint getAge()
{
return age;
}
publicvoid setAge(intage)
{
this.age=age;
}
publicString getPolicyType()
{
return policyType;
}
publicvoid setPolicyType(String policyType)
{
this.policyType=policyType;
}
publicint getPremiumAmount()
{
return premiumAmount;
}
publicvoid setPremiumAmount(intpremiumAmount)
{
this.premiumAmount=premiumAmount;
}
}
Add file with .drl extension to your classpath (src/main/resources). This file will contains all rules in plaintext
which can be easily modified and loaded at runtime if needed.

10. Integrating DROOLS With Mule ESB1
package com.drools.example
import org.mule.MessageExchangePattern;
import com.drools.example.Insurance;
global org.mule.module.bpm.MessageService mule;
dialect "mvel"
declare Insurance
@role('event')
end
rule "Policy 1 And Infant"
lock - on - active when
$insurance: Insurance(age <10 && policyType =="Policy1") then
modify($insurance) {
setPremiumAmount(20000)
}
end
rule "Policy 1 And Adult"
lock - on - active when
$insurance: Insurance((age >=10&&age <= 40) && policyType =="Policy1") then
modify($insurance) {
setPremiumAmount(30000)
}
end
rule"Policy1 And Older"
lock - on - active when
$insurance: Insurance(age >40 && policyType =="Policy1") then
modify($insurance) {
setPremiumAmount(40000)
}
end
rule "Policy 2 And Infant"
lock - on - active when
$insurance: Insurance(age <10 && policyType =="Policy2") then
modify($insurance) {
setPremiumAmount(21000)
}
end
rule "Policy 2 And Adult"
lock - on - active when
$insurance: Insurance((age >=10&&age <= 40) && policyType =="Policy2") then
modify($insurance) {
setPremiumAmount(31000)
}
end
rule"Policy2 And Older"
lock - on - active when
$insurance: Insurance(age >40 && policyType =="Policy2") then
modify($insurance) {
setPremiumAmount(41000)
}
end

11. Integrating DROOLS With Mule ESB
In rule file, we have defined import namespaces and packages statements.Then
we create the Insurance object to be used by our rule engine and followed by some
rules with conditions that explained earlier.
Define Spring Beans
You need to define spring beans in your configuration file (e.g. droolsexample.xml)
as shown below

12. Integrating DROOLS With Mule ESB
Call Rule Definition in Mule Flow
• Rule Definition can be call in Mule flow by defining below statement in
configuration file (droolsexample.xml)

13. Integrating DROOLS With Mule ESB
Mule Flow [Code]
<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:json="http://www.mulesoft.org/schema/mule/json"xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:wmq="http://www.mulesoft.org/schema/mule/ee/wmq"xmlns="http://www.mulesoft.org/schema/mule/core"
xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
xmlns:spring="http://www.springframework.org/schema/beans"
xmlns:bpm="http://www.mulesoft.org/schema/mule/bpm"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/httphttp://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/json http://www.mulesoft.org/schema/mule/json/current/mule-json.xsd
http://www.mulesoft.org/schema/mule/ee/wmqhttp://www.mulesoft.org/schema/mule/ee/wmq/current/mule-wmq-ee.xsd
http://www.mulesoft.org/schema/mule/bpmhttp://www.mulesoft.org/schema/mule/bpm/current/mule-bpm.xsd">
<bpm:drools/>
<spring:beans>
<spring:bean name="NoFactsBean" class="java.util.ArrayList"/>
</spring:beans>
<http:listener-configname="HTTP_Listener_Configuration" host="0.0.0.0" port="8081"doc:name="HTTPListenerConfiguration"/>
<flow name="mule-proj-flowFlow">
<http:listenerconfig-ref="HTTP_Listener_Configuration" path="/drools"allowedMethods="POST" doc:name="HTTP"/>
<wmq:object-to-message-transformer doc:name="Objectto Message"/>
<json:json-to-object-transformer returnClass="com.drools.example.Insurance" doc:name="JSON to Object"/>
<bpm:rules rulesDefinition="insuranceRules.drl"initialFacts-ref="NoFactsBean" doc:name="BPMRules"/>
<set-payload value="#[payload.object]" doc:name="SetPayload"/>
<json:object-to-json-transformer doc:name="Object toJSON"/>
</flow>
</mule>

14. Integrating DROOLS With Mule ESB
Testing
We will use postman to test all the above scenarios and hopefully, we will get
expected result back.

15. Integrating DROOLS With Mule ESB
Conclusion
Mule provided easy steps to integrate with DROOLS and same is explained in
above article. I hope you find this article interesting and provided required
information to integrate DROOLS with Mule flow.

16. ThankYou.