Re: [rules-users] Rookie question: best place to locate KnowledgeBase in web application?
ljnelson wrote: My question is: where is the best place to put the various parts, and what sort of synchronization do I need to worry about? I did not see any reference to these issues in the (massive, otherwise excellent) Drools documentation. Well, OK, that generated a lot of traffic. :-) Talking to myself here, let's expand this out a bit and say: OK, how would we do this inside a stateless session bean? I am loathe to write a resource adapter for Drools. Given that, and that I'm working with stateless sessions exclusively, I'm also willing to live with several instances of Drools--i.e. if I create the engine as an instance variable (or static variable) inside my SLSB, I'm willing to live with the fact that the container might (probably will) create several instances of my SLSB, and hence several instances of my rules engine--they'll all be reading the same rules information so should vend the same results. My main question, for the two of you still reading, is around synchronization: I understand that a StatelessKnowledgeSession is thread safe, but what about acquiring it? Where else, if anywhere, will I run into threading issues? Thanks, Laird -- View this message in context: http://old.nabble.com/Rookie-question%3A-best-place-to-locate-KnowledgeBase-in-web-application--tp26152111p26157126.html Sent from the drools - user mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] Rookie question: best place to locate KnowledgeBase in web application?
Hi Laird, In our web application we create one KnowledgeAgent and each session calls getKnowledgeBase to get the KnowledgeBase and then getStatelessSession to get a session. We have not had any threading issues. I'm pretty sure that each of those operations are thread-safe. Hope this helps, Steve rules-users-boun...@lists.jboss.org wrote on 11/02/2009 09:13:01 AM: [image removed] Re: [rules-users] Rookie question: best place to locate KnowledgeBase in web application? ljnelson to: rules-users 11/02/2009 09:16 AM Sent by: rules-users-boun...@lists.jboss.org Please respond to Rules Users List ljnelson wrote: My question is: where is the best place to put the various parts, and what sort of synchronization do I need to worry about? I did not see any reference to these issues in the (massive, otherwise excellent) Drools documentation. Well, OK, that generated a lot of traffic. :-) Talking to myself here, let's expand this out a bit and say: OK, how would we do this inside a stateless session bean? I am loathe to write a resource adapter for Drools. Given that, and that I'm working with stateless sessions exclusively, I'm also willing to live with several instances of Drools--i.e. if I create the engine as an instance variable (or static variable) inside my SLSB, I'm willing to live with the fact that the container might (probably will) create several instances of my SLSB, and hence several instances of my rules engine--they'll all be reading the same rules information so should vend the same results. My main question, for the two of you still reading, is around synchronization: I understand that a StatelessKnowledgeSession is thread safe, but what about acquiring it? Where else, if anywhere, will I run into threading issues? Thanks, Laird -- View this message in context: http://old.nabble.com/Rookie-question% 3A-best-place-to-locate-KnowledgeBase-in-web-application-- tp26152111p26157126.html Sent from the drools - user mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] Rookie question: best place to locate KnowledgeBase in web application?
I believe acquiring a StatelessKnowledgeSession is thread safe as well. Many members of the drools dev team are traveling at the moment, hence the slow response. --- On Mon, 11/2/09, ljnelson ljnel...@gmail.com wrote: From: ljnelson ljnel...@gmail.com Subject: Re: [rules-users] Rookie question: best place to locate KnowledgeBase in web application? To: rules-users@lists.jboss.org Date: Monday, November 2, 2009, 9:13 AM ljnelson wrote: My question is: where is the best place to put the various parts, and what sort of synchronization do I need to worry about? I did not see any reference to these issues in the (massive, otherwise excellent) Drools documentation. Well, OK, that generated a lot of traffic. :-) Talking to myself here, let's expand this out a bit and say: OK, how would we do this inside a stateless session bean? I am loathe to write a resource adapter for Drools. Given that, and that I'm working with stateless sessions exclusively, I'm also willing to live with several instances of Drools--i.e. if I create the engine as an instance variable (or static variable) inside my SLSB, I'm willing to live with the fact that the container might (probably will) create several instances of my SLSB, and hence several instances of my rules engine--they'll all be reading the same rules information so should vend the same results. My main question, for the two of you still reading, is around synchronization: I understand that a StatelessKnowledgeSession is thread safe, but what about acquiring it? Where else, if anywhere, will I run into threading issues? Thanks, Laird -- View this message in context: http://old.nabble.com/Rookie-question%3A-best-place-to-locate-KnowledgeBase-in-web-application--tp26152111p26157126.html Sent from the drools - user mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
[rules-users] Rookie question: best place to locate KnowledgeBase in web application?
I'm going to be interacting with a KnowledgeBase in a web application. I do not expect the rules to change during the running of the application. I will be using StatelessKnowledgeSessions exclusively. My question is: where is the best place to put the various parts, and what sort of synchronization do I need to worry about? I did not see any reference to these issues in the (massive, otherwise excellent) Drools documentation. I assume that the best strategy is to: - Locate the KnowledgeBase in the ServletContext upon startup - Read in the rule base at startup in a synchronized block (I don't think the servlet specification guarantees that a ServletContextListener is thread-safe at startup, but maybe this is overkill) - During runtime, synchronize on the rule base while acquiring a StatelessKnowledgeSession from the ServletContext - Use the acquired StatelessKnowledgeSession freely, without any further concern for locking (after all, it's stateless, right?) Could someone please correct me if any of these statements is wrong? Thanks, Laird ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
