Dear all, How do we modify a global variable with mvel dialect inside rules file without getting java.lang.UnsupportedOperationException: External Variable identifer='allowance' type='class java.lang.Double' is final, it cannot be set [testng] at org.drools.base.mvel.DroolsMVELGlobalVariable.setValue(DroolsMVELGlobalVariable.java:37) [testng] at org.drools.base.mvel.DroolsMVELFactory.createVariable(DroolsMVELFactory.java:199) [testng] at org.mvel.ast.AssignmentNode.getReducedValueAccelerated(AssignmentNode.java:80) [testng] at org.mvel.MVELRuntime.execute(MVELRuntime.java:88) [testng] at org.mvel.CompiledExpression.getValue(CompiledExpression.java:108) [testng] at org.mvel.MVEL.executeExpression(MVEL.java:230) [testng] at org.drools.base.mvel.MVELConsequence.evaluate(MVELConsequence.java:47) [testng] at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:550) [testng] at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:514) [testng] at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:462) [testng] at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:424) This is how I did it: Java file: public void run(){ Double allowance = new Double(0); workingMemory.setGlobal("allowance", allowance); workingMemory.fireAllRules(); } Rules: global Double allowance dialect "mvel" rule "Has Wife" no-loop salience 20 when e: Employee() income:Income() eval( e.isWife() ) then System.out.println("Has Wife"); allowance = allowance + 5000; end This works if I use java as the dialect. Have I missed something? Thanks in advance, -- It's not going to be like this forever Blog: http://joshuajava.wordpress.com/