Got the Rule Execution Server running. Pretty cool. Next step is to see how to incorporate nested objects. I've seen the Game of Life example, but somehow missed how it uses nested objects. In my case, the objects mimic a relational database, so you might have A Dog Kennel which contains many Pets, which have many owners. (maybe more than one owner per pet, but I'm not really worried about that) I'm wondering if there is a best practice in Drools for handling relations. Would this be best handled at the time of fact insertion, or is there a way to show the derivations of the fact types in the rules? Perhaps this is best done in the DRL? Thanks, Robert Costello