Re: [rules-users] Working memory - database synchronisation approach
fyi - There may be simpler/cleaner ways of doing it, but if you wish to ensure that you
always have access to your Spring context even when you're out roaming on a separate
thread, you can get static access to the context like this below. I use it so that I can
use Spring to help me get data for Guvnor enums:
/**
* Maintains a static reference to a Spring {@link ApplicationContext}, and a
* static getContext() method, which will initialize the context if necessary.
*
* @author Stephen Masters
*/
public class GuvnorEnumContext {
private static ApplicationContext ctx = null;
GuvnorEnumContext() {
}
GuvnorEnumContext(ApplicationContext applicationContext) {
ctx = applicationContext;
}
public static ApplicationContext getContext() {
if (ctx == null) {
ctx = new AnnotationConfigApplicationContext(GuvnorEnumConfig.class);
}
return ctx;
}
}
/**
* Due to the fashion in which Guvnor enums are invoked, we maintain a
* static reference to the Spring {@link ApplicationContext} in the
* {@link GuvnorEnumContext}. This ensures that the context is only instantiated
* once.
*/
private static MyFinder finder() {
return (MyFinder) GuvnorEnumContext.getContext().getBean("myFinder");
}
On 28 Mar 2013, at 10:17, Stephen Masters <stephen.masters(a)me.com> wrote:
That sounds like a decent design to me. I don't much like having
persistence inside the rules.
The issue you have seems more related to the fact that you're executing the rules in
a separate thread than your persistence design. I don't suppose you're actually
spawning a thread from inside a JTA transaction in which to run your rules?
Steve
On 28 Mar 2013, at 08:46, riri <irina.adam(a)gmail.com> wrote:
> Hello everyone,
>
> I am currently working on a Spring, Hibernate, Bitronix project and am
> trying to integrate Drools functionality. I have a set of JPA Entities that
> I can manage using Spring Data and Hibernate and I would like to use these
> entities as facts inside a StatefulKnowledgeSession. As I understand it, I
> need to have some mechanism of keeping the facts inside the working memory
> in sync with the database and what I mean by that is:
> 1. update the facts in working memory when they are changed from outside
> 2. update the facts in the database when a RHS part of a rule changes
> properties
>
> This article http://www.ibm.com/developerworks/java/library/j-drools5/
> <http://www.ibm.com/developerworks/java/library/j-drools5/> gives some
> pointers on how to achieve 1. using AOP but in my case I do not have a
> global knowledge session to insert, I need to be able to create a knowledge
> base for each user of the application since each user will need to have his
> own set of rules independent from other users.
>
> What would be the best practices for achieving the synchronisation?
> Currently for 1. I am updating the fact manually by retrieving the object
> and calling update from java code. For 2. I have a
> WorkingMemoryEventListener that is configured as a Spring @Component with
> autowired services that can perform CRUD actions on entities and which are
> called on objectUpdated.
>
> I am new to all these technologies so I do not know if this is a good way to
> go. I have a unit test where a rule modifies a property and the object is
> updated in the database but if the Thread with the fireUntilHalt method is
> not paused, the test finishes and the JTA manager is shut down before the
> rules can fire and the transaction in the objectUpdated can be executed.
>
> I would be very grateful for any insight from the more experienced users
> that have come across such requirements before.
>
> Best regards
>
>
>
> --
> View this message in context:
http://drools.46999.n3.nabble.com/Working-memory-database-synchronisation...
> Sent from the Drools: User forum mailing list archive at Nabble.com.
> _______________________________________________
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