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

[Oleg Yavorsky]

Chris,

I'll try to dig it a little too. My problem is that I need to proxy concrete classes as they are generated from XSD using Castor. If I find workaround I'll let you know.

Oleg.

Chris West <crayzfishr at gmail.com> wrote: 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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