hi , i m new in drools, i m reading the Drools-JBoss-Rules-5.0-Developers-Guide book in which i found a validation rule example on its chapter 3. In this exemple, global variables were set into the session with two methods shown in this code : ... session = knowledgeBase.newStatelessKnowledgeSession(); session.setGlobal("reportFactory", reportFactory); session.setGlobal("inquiryService", inquiryService); ... and these variables qualified as immutables, were called from the RuleContext public static void error(RuleContext drools, Object... context) { KnowledgeRuntime knowledgeRuntime = drools .getKnowledgeRuntime(); ValidationReport validationReport = (ValidationReport) knowledgeRuntime.getGlobal("validationReport"); ReportFactory reportFactory = (ReportFactory) knowledgeRuntime.getGlobal("reportFactory"); ... and for other variables(or facts ) the Command interface was used instead : List<Command> commands = new ArrayList<Command>(); commands.add(CommandFactory.newSetGlobal( "validationReport", report)); commands.add(CommandFactory .newInsertElements(getFacts(customer))); session.execute(CommandFactory .newBatchExecution(commands)); i m looking for accuracy in understanding when and which to use each method.