There are a couple different options available. I haven't tried it but some of what you are trying to do sounds suspiciously like what you are trying to do is a workfow process or rules plan. Which might mean you want to look at planner or consider how you are approaching the problem. If they were in the same group I know you can literally do what you want by adding the salience keyword to one of your rules. example - rule "print mail messages" salience -100 // run this after other rules have finished dialect "mvel" when $m : Message( ) then System.out.println( "Message was "+$m ); end I am not sure if it works between groups though I thought there were ways to state order of group activation but that has never been part of the documentation I use so I can't help you much there. But as a third option I would suggest if you are using mvel you just use the feature of the language to do null checks in the business logic if that is feasible for you. Example $var: user.?manager.name is supposedly functionally equivalent to writing: if (user.manager != null) { $var=user.manager.name; } else { $var=null; } So you might just be able to test the data more elegantly inline. But it really depends on what you are trying to do and why. Hope this helped! If not I expect someone more familiar with the planning or enterprise tools may speak up. Zachary -- View this message in context: http://drools.46999.n3.nabble.com/Validation-flow-defer-expression-evalua... Sent from the Drools: User forum mailing list archive at Nabble.com.

Hi, I have added a subprocess to the flow, but the exception still occurs: Caused by: [Error: null pointer or function not found: getName] [Near : {... manager.getName().equals("tes ....}] Would anyone have suggestions or know about best practices for handling this kind of scenario? Thanks -- View this message in context: http://drools.46999.n3.nabble.com/Validation-flow-defer-expression-evalua... Sent from the Drools: User forum mailing list archive at Nabble.com.