[rules-users] Re: Using JDK dynamic proxies as facts

[Chris West]

Oleg,

So far I have not been successful.  I've just posted my thoughts to this
list (under the subject "The effect of not using shadow facts").  Concerning
the class names, my rules only match on an interface type implemented by the
proxies, so the actual class type of the instance does not matter.

-Chris

On 7/13/07, Oleg Yavorsky <oleg_yavorsky at yahoo.com> wrote:
>
> Chris,
>
> I'm thinking about using dynamic proxies in my rules too. I'll be glad to
> hear about your success with them. I think that there could be problem with
> matching of facts as they won't be of original class but of Proxy$... one.
> CGLIB approach doesn't have such problem as it just modifies original
> classes' bytecode. I could be wrong, anyway.
>
> Oleg.
>
> *Mark Proctor <mproctor at codehaus.org>* wrote:
>
> That is not the only thing that determines shadowing. If you look the
> shadowing is actually determined here:
>             if ( !ruleBase.getConfiguration().isShadowProxy() || cls ==
> null || !ruleBase.getConfiguration().isShadowed( cls.getName() ) ) {
>                 return;
>             }
> By default shadowing is turned on for all (none final) bjects, except
> stuff in the org.drools namespace, you have to set exclusion lists.too. So
> if your package has a null namespace it will still attempt to shadow it.
>
> Mark
>
> Chris West wrote:
>
> OK, I just solved my own problem.  My proxy had no package, since the jdk
> based proxy is only in a package if it has at least 1 non public interface,
> according to the javadoc.
>
> The suspect code beginning on line 333 is:
>
>             String pkgName = cls.getPackage().getName();
>             if ( "org.drools.reteoo".equals( pkgName ) || "org.drools.base".equals(
> pkgName ) ) {
>                 // We don't shadow internal classes
>                 this.shadowEnabled = false;
>                 return;
>             }
>
> The getPackage() method returns null.  In this case, it would be good if
> JBoss Rules handled the null and went on to shadow the object anyway, since
> it is obviously not in the org.drools packages.
>
> Now I'll continue trying to build a test case for my original problem.
>
> Shall I enter a JIRA for this issue?
>
> Thanks,
> -Chris West
>
> On 7/12/07, Chris West <crayzfishr at gmail.com> wrote:
> >
> > Hello,
> >
> > I'm trying to use objects that are generated as dynamic proxies (through
> > the java.lang.reflect.Proxy class) as facts in JBoss Rules 4.0 MR3.  My
> > project was using CGLib to generate proxies, and they were working just fine
> > in 3.0.6.  However, when I tried 4.0, the CGLib based proxies seemed to
> > have a final method that kept the proxies from being proxied as shadow
> > facts.  So I rewrote my code to try to use JDK based proxies, and version
> > 4.0 MR3 accepts them and apparently creates shadow facts, but now my
> > rules don't fire correctly.
> >
> > So, in an attempt to create a simple program to illustrate the problem,
> > I ran into a different problem.  The attached eclipse project illustrates
> > this problem.
> >
> > The error is:
> >
> > java.lang.NullPointerException
> >     at org.drools.reteoo.Rete$ObjectTypeConf.<init>(Rete.java:333)
> >     at org.drools.reteoo.Rete.assertObject(Rete.java:152)
> >     at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java
> > :190)
> >     at org.drools.reteoo.ReteooWorkingMemory.doInsert(
> > ReteooWorkingMemory.java:70)
> >     at org.drools.common.AbstractWorkingMemory.insert(
> > AbstractWorkingMemory.java:772)
> >     at org.drools.common.AbstractWorkingMemory.insert (
> > AbstractWorkingMemory.java:584)
> >     at com.sample.DroolsTest.main(DroolsTest.java:42)
> >
> > Has anyone successfully used JDK based dynamic proxies as facts?
> >
> > Thanks,
> > -Chris West
> >
> >
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