Rules With Drools

Rules with Drools

Gaurav Kohli

Saket Vishal

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What about this? Akshay Kumar, 32, Chandini Chowk, Delhi, 110006

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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 Drools

Basically, 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 Drools

DSL – Domain Specific Languages

Human readable rules

Demo

Behind Drools

RETE

Behind Drools

When not to use 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 or maintained over time.

Alternatives to 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

Advanced Drools