1. Rules – Where conditions are specified (If a then b)
2. Facts – Simple objects (POJOs). E.g, a Bank Account fact consists of an account number, someone’s id and balance.
3. Knowledge Base –is where rules are built and loaded into a structure that gets implemented by the Rete algorithm.
4. Session – Here facts are placed. Facts are inserted into a session. A session can be State less or State full. Facts in the statefull shall be present in a constant rule alignment once
Objects used by the Drools are market out by the rules and patterns which are responsible for invoking the certain actions: Drool objects are considered as the Java objects. They are usually presented by the XML schemas or instances of the Java classes.A patter being a coded expression is involved in the manipulation of 1 or more than 1 objects so that to create a pattern for making, adapting behavior, according to the designed logic.Working Memory drools stores its objects