What is Drools

Drools is a Business Logic integration Platform (BLiP) written in Java. It is an open source project but there are community and enterprise versions of the product also available. Drools helps in segregating the business layer from our application layer. The rules are written in .drl file(Domain rule language file)

Logic, or rules in our case, are pieces of business knowledge and are expressed as,

When some conditions are true then do something

Drools is split in two main parts:

  • Authoring: Involves the creation of rules files (.DRL) which contain the rules which are fed into a parser. The Parser checks for correct syntax of the rules and produces an intermediate structure that describes the rules.
  • Runtime: Creation of working memory and handling the activation which means how to load the rules to the engine and how to execute them.