These classes are not part of the "stable API", which is considered safe, i.e., not threatened by future changes. Also, the lack of javadoc is appalling. And if that's not enough, creating and maintaining any but the simplest LHS compositions programmatically is a mind-straining exercise, for which you need a very, very good reason,... A much easier way for generating rules programmatically is based on templates. If your goal is simply speeding up the Knowledge Base initialization process, then the standard procedure is to use (Drools 5): // create precompiled package OutputStream os = new FileOutputStream( "src/main/rules/x/y.pkg" ); ObjectOutputStream oos = new ObjectOutputStream( os ); oos.writeObject( kBuilder.getKnowledgePackages() ); oos.close(); // load precompiled packag InputStream is = new FileInputStream( "src/main/rules/movie/Movie.pkg" ); ObjectInputStream ois = new ObjectInputStream( is ); @SuppressWarnings("unchecked") Collection<KnowledgePackage> kpkgs = (Collection<KnowledgePackage>) ois.readObject(); ois.close(); kBase.addKnowledgePackages( kpkgs ); This is equivalent to kBase.addKnowledgePackages( kBuilder.getKnowledgePackages() ); but can, obviously, done by different programs. -W 2009/8/24 Ashish Soni <learnspring(a)gmail.com&gt;