Node 1, 2 and 3 will have their own singleton instances of a Process Engine. All servers are in an Active-Active configuration which means requests are routed to each node in a more or less round robin manner.
Scenario 1 A request is routed to Node 1 which starts a process with the id 100. Activiti flushes this state immediately to the database. Another request is routed to node 2 where a user may want to carry out a human task (such as approve) on the process instance with same id i.e. 100. Although the process instance is not in memory of the 2nd node if the process engine on this particular node queries the database it will get it, load it and allow the user to carry out the task. So there is no issue. However since JBPM 5.4 does not flush it's state immediately to the database this will cause issues. Am I right?
Scenario 2 This is a maker checker scenario. Two checkers are logged into Node 1 and Node 2 respectively. The first checker approves an work item. The second checker approves the same work item. How does Activti handle this?. Will it throw an exception or will it behave in a idempotent manner and allow both the operations to succeed? And How does JBPM handle this?
Activiti is created with clustereability in mind. scenario 1 will work. Scenario 2: one will win, the other one gets an exception (ActivitiOptimisticLockingException)
