I'm in the process of upgrading from 2.1 to 3.0 and I've noticed the signature for knowledgeHelper.modifyObject( Object object ) has changed to include a FactHandle for it. Architecturally, does this imply that a list of all fact handles for all asserted objects has to be maintained in order for modifications to occur? Or would the following call be the way out? knowledgeHelper.modifyObject( knowledgeHelper.getWorkingMemory() .getFactHandle( someObject ), someObject ); (curiously, the above could gives me NPE's on the factHandle for someObject). DP -- View this message in context: http://www.nabble.com/Modify-Object-and-Fact-Handles-tf4132409.html#a1175... Sent from the drools - user mailing list archive at Nabble.com.