Introduction to Drools

Enterprise systems usually have multiple layers. From top to bottom they are: Presentation Layer, Business Logic Layer, and Persistence Layer. The Middle Layer — Business logic represents the core of the application where all of the business processes and decisions take place.

We had lot of frameworks which covers the User Interface and the Service layer aspects but no proven framework/tool to handle the Business logic layer.

Also the need to build more and more complex systems is increasing. We're trying to automate all kinds of business processes and implement complex business decisions. However, these processes and decisions are not very well represented using traditional programming languages such as Java and hence needed a framework/tool for the business layer as well and that gave rise to Drools (Rule Engine).

Drools is part of the JBoss Enterprise BRMS product since federating in 2005, is a Business Rule Management System (BRMS) and rules engine written in Java which implements and extends the Rete pattern-matching algorithm. Now let's talk about what is a Rule Engine.