Hello. I'm just a newbie in this jBPM world but have runned into problems trying to develop something similar (a workflow with MDB action consumers, where the tasks were modelled as JPA entitites in an EJB3 context). I dind't find a way to perform pessimistic locking for the entities (I have the idea that it's not supported) and tests with concurrent threads led me to very odd results. About detection of conflicts in optimistic locking, I also think that table versioning is only detecting problems when committing, when the version numbers mismatch can be detected. Another weird thing is READ_UNCOMMITED Hypersonic transaction isolation level mixed with optimistic locking. Changing to a RDBMS with a real transaction isolation leads to really different results when using optimistic locking (as chances to have obsoleted versions of the entities are bigger than with Hypersonic). Hope it helps. Regards. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3972489#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...