Kris, ActionNodeInstanceImpl is a stateless representation of a node in a process, and the ActionNode it references is also stateless. So why do you accesss it indirectly? protected ActionNode getActionNode() { return (ActionNode) getNode(); } protected Node getNode() { return this.processInstance.getRuleFlowProcess().getNode( this.nodeId ); } -------------------- private Map nodes; final Long idLong = new Long( id ); Look at PrimitiveLongMap and how its used, means no ObjectWrappers and uses up a lot less memory than HashMap - as well as being marginally faster. It is meant for situations where you no the keys are issued incrementally, we use a key recycling class PrimitiveLongStack to ensure we don't end up with gaps. -------------------- I have MVELAction working now in the build framework. I don't really like actionNode.getAction() which returns an Object, the execution implemtentation is encapsulated so just actoinNode.execute( wm ) should be fine, which then delegates to the MVELAction. public void testSimpleAction() throws Exception { final Package pkg = new Package( "pkg1" ); ActionDescr actionDescr = new ActionDescr(); actionDescr.setText( "list.add( 'hello world' )" ); PackageBuilder pkgBuilder = new PackageBuilder( pkg ); final PackageBuilderConfiguration conf = pkgBuilder.getPackageBuilderConfiguration(); MVELDialect mvelDialect = ( MVELDialect ) pkgBuilder.getDialectRegistry().getDialect( "mvel" ); PackageBuildContext context = new PackageBuildContext(); context.init( conf, pkg, null, pkgBuilder.getDialectRegistry(), mvelDialect, null); pkgBuilder.addPackageFromDrl( new StringReader("package pkg1;\nglobal java.util.List list;\n") ); ActionNodeImpl actionNode = new ActionNodeImpl(); final MVELActionBuilder builder = new MVELActionBuilder(); builder.build( context, actionNode, actionDescr ); final RuleBase ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage( pkgBuilder.getPackage() ); final WorkingMemory wm = ruleBase.newStatefulSession(); List list = new ArrayList(); wm.setGlobal( "list", list ); ((Action)actionNode.getAction()).execute( wm ); assertEquals("hello world", list.get(0) ); } Mark