Hi,   In jBPM4.4 you can deploy a jPDL with the same name multiple times. The different versions automatically get a different version number and processInstances will keep using the version that was current when the processInstance started. You do not need to select specified Process Definitions upon engine startup. All is retrieved from the database as needed.   In jBPM5.4 things seem to be different. If I am correct the Knowledge base needs to be filled at startup with all Process Definitions which are needed by any running process. If I need multiple versions of the same Process Definition in the kBase to complete process instances started with a different version, it seems I cannot use the same id for the different "versions" of the "same" process definition. Adding two process definitions with the same id  but a different version number does not seem to work.   1) Am I right so far?   If (1) == yes then 2) what it the use of the version number? 3) will everything work if I change the ProcessDefinitions with as id the original processDefinition id concattenated with the version number?   4) does Guvnor support automatic version management?: create BPMN with id a.b.c , start processInstance for this BPMN, change BPMN (keep id, but increment version), start second processInstance. ProcessInstance 1 will keep using version 1 of BPMN, ProcessInstance 2 will use the updated version of the BPMN   If (4) == no then how does Guvnor handle changes to BPMN definitions? Are you supposed to upgrade all running versions of a Process Definition?     Thanks a lot!   Michiel   ----------------- http://www.codessentials.com - Your essential software, for free! Follow us at http://twitter.com/#!/Codessentials