This isn't a question that can be answered in a few lines. Build a DRL file with a simple rule and then following what it does at the ReteooBuilder.addRule(Rule) method. Likewise follow an insert method when you insert an object.Have been reading about how Rete operates and how Drools implements Rete and so on .. and that Rete builds a network of nodes and each node is a pattern and has memory of facts which satisfy the pattern …. just as a curiosity, how does this all work internally ? what does it mean when they say that it builds a network .. and nodes are shared and attached .. what does really happen internally ?