Rules with Drools

Gaurav KohliSaket Vishal

Recognize this?

3.1732

What about this?

Akshay Kumar,32, Chandini Chowk,

Delhi, 110006

Lets talk about

Akshay Kumar

Some rules on names• First Name + Last Name• First Name + First Name + Last Name• (First Name)+ + Last Name

• First Name + First Name– Saket Vishal

Implementing these rules in Java

Demo

Problems in implementing with Java

• Frequent changes to rules(conditions)• Lack of centralization of rules– Difficult to analyse and manage

• Non technical people(Business Analysts ..) can't create/update rules

• Performance

Introducing DroolsBasically, a rule engine

Rule Engine: Platform that provides functionality to manage rules

Rule: An if else condition (Business Logic)

Rules in Drools

Demo

The Big Picture

Back to rules in DroolsDSL – Domain Specific Languages– Human readable rules

Demo

Behind Drools• RETE

Behind Drools

If your business logic is well defined/static and doesn't change often, you don't need to change rules at run-time.

If your rules are simple, self-contained, and usually spanning only a single object (for example, a check that user's age is less than 21).

If you have a memory constrained environment.

If your project is a one-shot effort and it will never be used again ormaintained over time.

When not to use Drools

ILOG (now IBM)—JRules

Fair Isaac—Blaze Advisor

Corticon's BRMS,

Haley (now Oracle) Business Rules Engine

Pegasystems—PegaRules,

Production Systems Technologies—OPSJ

CLIPS

OpenRules or Jess

Alternatives to Drools

Advanced Drools• Drools Flow – Loan approval

• Drools Fusion– Fraud detection

• Drools Guvnor– BRMS

?

References• Drools

• http://www.jboss.org/drools• Drools JBoss Rules 5.0 Developer's Guide

• RETE• http://en.wikipedia.org/wiki/Rete_algorithm

Thank You!