Re: [rules-users] The effect of not using shadow facts

Chris, I found and developed an intermediate solution that shall work for your proxies. If it is not possible to create a shadow fact for a class that is asserted (because the class is final or whatever), the engine goes up in the class hierarchy, looking for a class or interface for which is possible to create the proxy, but that still matches all ObjectTypes available in the rule base matched by the original class. The analysis is a bit complex, specially because new rules with new object types can be dynamically added to the rule base, but I believe the solution will work for JDK proxies and the most common proxy frameworks out there, that usually don't proxy multiple unrelated interfaces at once. So, I ask you please to get latest snapshot from the repository and try it out for your use case and report back to the list the results, since seems there are a few other people using similar things. Thanks, Edson 2007/7/17, Chris West <crayzfishr(a)gmail.com&gt;: > > Is that still true if the equals() and hashcode() methods are only based > on the identity fields of the object (which cannot change)? > > -Chris West > > On 7/17/07, Mark Proctor <mproctor(a)codehaus.org&gt; wrote: > > > > you only need to use modifyRetract if the object is inserted. The > > reason for this is if you change field values on your facts we will not be > > able to remove them from our various internal hashmaps; thus the need to > > remove first prior to any changes, then make the changes and then insert it > > again. We can't allow users to just call update() as we have no idea what > > the old values where, thus we cannot find the objects in our hashmaps. > > > > Mark > > Chris West wrote: > > > > Mark, > > > > Using modifyRetract and modifyInsert seems to fix the problem (at > > least in my test case I finally created). I'll try this on my real code. > > > > My only concern here is that it puts the burden on the rule author to > > know whether things are being shadowed or not. For shadowing that is > > explicitly turned off this is ok. But for implicit non-shadowing based on a > > class being final, this is not at all obvious to the rule auther. > > > > Is there any way to have this hidden such that I can still call > > "update" but have it use "modifyRetract" and "modifyInsert" instead? > > > > Also, I'm curious why I have to call modifyRetract before I start > > modifing the object, since the engine does not know about my modifications > > anyway until I call update or modifyInsert? By the way, I was unable to use > > the block setter approach in the rule consequence due to not having set > > methods for modifying my objects. > > > > Thanks, > > -Chris West > > > > On 7/17/07, Mark Proctor <mproctor(a)codehaus.org > wrote: > > > > > > If you do not have shadow facts you cannot use the update() method, > > > it will leave the working memory corrupted. Instead you must manage this > > > yourself, before you change any values on the object you must call > > > modifyRetract() and after you hvae finished your changes ot hte object call > > > modifyInsert() - luckily if you are doing this in the consequence you can > > > use the MVEL modify keyword combined with the block setter and it does this > > > for you: > > > modify ( person ) { age += 1, location = "london" } > > > > > > Mark > > > Chris West wrote: > > > > > > Hello, > > > > > > With prior versions of JBoss Rules (3.0.5) I have been using JDK > > > generated dynamic proxies as facts, and they have been working fine. > > > However, after upgrading to JBoss Rules 4.0.0MR3, I cannot seem to > > > get the dynamic proxies to work as facts. It seems that even though a rule > > > fires that changes a field on the proxy, a second rule that should not be > > > activated after the update still fires. > > > > > > According to the JDK javadoc documentation, dynamic proxies are > > > created as final. My assumption is that JBoss Rules is not creating Shadow > > > facts for these since they are final. After reading the JIRA at > > > http://jira.jboss.com/jira/browse/JBRULES-960, I now am questioning > > > what the effect of not using shadow facts is on the engine. The relevant > > > part of that is: > > > > > > "The problem is that SpringAOP is generating a proxy whose methods > > > equals() and hashCode() are "final". As drools must either override these > > > methods in the shadow proxy or not shadow the fact at all, I'm disabling > > > shadow proxy generation for this use case. > > > It is really important to note that if you are asserting SpringAOP > > > proxies as facts into the working memory, you will not be able to change any > > > field value whose field is constrained in rules or you may incur in a memory > > > leak and non-deterministic behavior by the rules engine. Unfortunately there > > > is nothing we can do about, since when SpringAOP makes the methods equals > > > and hashcode final, we can't override them anymore and as so, we can't > > > shadow them." > > > [ Show » <http://jira.jboss.com/jira/browse/JBRULES-960> ] > > > Edson Tirelli<http://jira.jboss.com/jira/secure/ViewProfile.jspa?name=tirell... > > > [02/Jul/07 03:29 PM] The problem is that SpringAOP is generating a > > > proxy whose methods equals() and hashCode() are "final". As drools must > > > either override these methods in the shadow proxy or not shadow the fact at > > > all, I'm disabling shadow proxy generation for this use case. It is really > > > important to note that if you are asserting SpringAOP proxies as facts into > > > the working memory, you will not be able to change any field value whose > > > field is constrained in rules or you may incur in a memory leak and > > > non-deterministic behavior by the rules engine. Unfortunately there is > > > nothing we can do about, since when SpringAOP makes the methods equals and > > > hashcode final, we can't override them anymore and as so, we can't shadow > > > them. > > > > > > Although I'm not using SpringAOP, I believe my facts are not being > > > shadowed. > > > > > > Is it true that not using shadow facts may lead to non-deterministic > > > behavior? Prior to shadow facts, the engine seemed to handle it. Any > > > chance of reverting back to the old style of truth maintenance in the case > > > of not using shadow facts. > > > > > > I apologize if I'm not on the right track here. My only test case > > > for my problem is the entire application right now, so I cannot offer it for > > > discussion. Any advice would be greatly appreciated. > > > > > > Thanks, > > > -Chris West > > > > > > ------------------------------ > > > > > > _______________________________________________ > > > rules-users mailing list > > > rules-users(a)lists.jboss.org > > > > > > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > > > > > _______________________________________________ > > > rules-users mailing list > > > rules-users(a)lists.jboss.org > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > ------------------------------ > > > > _______________________________________________ > > rules-users mailing list > > rules-users(a)lists.jboss.org > > > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > > > _______________________________________________ > > rules-users mailing list > > rules-users(a)lists.jboss.org > > https://lists.jboss.org/mailman/listinfo/rules-users > > > > > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > > -- Edson Tirelli Software Engineer - JBoss Rules Core Developer Office: +55 11 3529-6000 Mobile: +55 11 9287-5646 JBoss, a division of Red Hat @ www.jboss.com _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users