[rules-users] Questions concerning Java and rules / Flexibility

I am a complete novice concerning Drools and have some basic questions, which arised after studying the drools documentation and some examples as well. As far as I got it right, you have two possibilities to work with drools 1) You write a java program, rules / actions are hard coded inline or saved in text files / excel sheets / XML files etc. After importing the necessary drools classes you call the drools interface routines, with the following functionalities: load rules, providing working memory, adding facts und finally starting the rule engine (e.g. firing rules). 2) You use the capabilities of the Drools GUI tools (such as Guvnor), which allows entering rules, objects and actions via GUI tools. Here, I don't get the point whether a part of the java code is generated automatically, or whether you have to write your java classes by yourself, as presented in possibility 1 (above), but without coding the rules by yourself in the source code / external input files. I would be very pleased, if anyone could explain me the essential difference between the two approaches and accordingly tell me what the advantage of using method 2) would be in contrast to method 1), particularly concerning the necessary java coding. --- Well and there would be another question, if you write down your rules and the corresponding software, which accesses the rules, is it possible to add some rules later, without rewriting/recompiling your software? Thanks in advance! Cheers, Martin.