Bing Lim [https://community.jboss.org/people/binglim] created the discussion "Re: Is it possible to get the StatefulKnowledgeSession/processInstance from solely its ID?" To view the discussion, visit: https://community.jboss.org/message/752102#752102 -------------------------------------------------------------- Hi Maciej, Thanks for your response. I implemented persistence but I'm thinking that there might be configuration problems that's causing the error I have right now. The exceptions I got are: java.lang.IllegalStateException: java.lang.reflect.InvocationTargetException           at org.drools.persistence.jpa.KnowledgeStoreServiceImpl.buildCommandService(KnowledgeStoreServiceImpl.java:143)           at org.drools.persistence.jpa.KnowledgeStoreServiceImpl.newStatefulKnowledgeSession(KnowledgeStoreServiceImpl.java:67)           at org.drools.persistence.jpa.JPAKnowledgeService.newStatefulKnowledgeSession(JPAKnowledgeService.java:122)           at com.sample.ProcessMain.main(ProcessMain.java:62) Caused by: java.lang.reflect.InvocationTargetException           at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)           at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)           at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)           at java.lang.reflect.Constructor.newInstance(Unknown Source)           at org.drools.persistence.jpa.KnowledgeStoreServiceImpl.buildCommandService(KnowledgeStoreServiceImpl.java:129)           ... 3 more Caused by: java.lang.NullPointerException           at org.drools.persistence.SingleSessionCommandService.<init>(SingleSessionCommandService.java:168)           ... 8 more Regarding the database, is the databse implemented within JBPM? By using JPAKnowledgeService and EntityManager, does it has a specific database that stores the information I need? I have attached the files in a zip folder in the original post, if you need any additional information. Thanks a lot for offering your help and I look forward to hearing from you. Best, Bing -------------------------------------------------------------- Reply to this message by going to Community [https://community.jboss.org/message/752102#752102] Start a new discussion in jBPM at Community [https://community.jboss.org/choose-container!input.jspa?contentType=1&...]