Drools business rule engine tutorials.
There are 2 main parts of Drools: Authoring & Runtime
Creation Rules files (.DRL) are involved in authoring process. They consists of rules that are being fed to a parser. Correct syntax of rules is checked by parser which creates intermediate structure so that to describe certain rules. Then it is passed on to Package Builder that creates the packages. After this, any code generation as well as compilation is undertaken that is essential to create package.