Re: [rules-dev] Compiling drools-5 to .NET -- issue with ClassLoaders

Hi Mike, Do you remember what you needed to do for drools3.0? I had earlier compiled drools 4.0 and it seemed to work without any major problems. Where can I find some documentation on the ASM and where drools picks up the classes from while generating the "in-situ" classes? Thanks, Krishna. -- http://kpowerinfinity.wordpress.com http://www.linkedin.com/in/kpowerinfinity On Thu, Sep 3, 2009 at 5:31 AM, Michael Neale<michael.neale(a)gmail.com> wrote: > Hi Krishna - I don't think the .Net version on the codehaus is kept > that up to date, so its probably a good thing you are doing what you > are doing with the latest. > > Yes, those accessor classes are indeed lazily generated and loaded > "in-situ" - this is for fast access of fields in the alpha network > which can be hit hard and often... an inlined version of the ASM > library is used to do this. > > I am pretty sure that even in drools 3 we did something like this > (also using ASM) and that was able to work with IKVM - so there must > be some small change that has made the IKVM classloader angry... > > On a barely related note: is it worth thinking about a Source to > Source translator to C# - there are a few around (ILog even open > sourced one, although it didn't cope with Generics last I checked...) > ? > > > Michael. > > On Wed, Sep 2, 2009 at 11:56 PM, kpowerinfinity<kpowerinfinity(a)gmail.com> wrote: >> Hello, >> >> I've been trying to compile the latest version of drools to .NET for a >> few days now. However, due to the classloaders structure, the classes >> in the org.drools.base.extractors.* are not found by the classloader, >> and the execution stops with a NoClassDefFoundError for classes in >> that package. >> >> Here's some details about the setup: >> Drools version: 5.0.1 >> IKVM Version: 0.40.0.1 >> >> I have successfully compiled all the required libraries into a DLL >> using IKVM, and a simple rule (containing a null LHS) runs >> successfully, all the classes are found, and the rule engine produces >> the correct output. However, when I add a condition into the LHS, it >> fails because it can't find one of the classes in >> /org.drools.base.extractors..*Reader/ >> >> A sample rule I am using is: >> """ >> package package >> import rules.Customer >> import rules.VoucherSeries >> >> rule "everything free for Krishna" >> >>        when >>                $c : Customer( firstname == "Krishna" ) >>        then >>                VoucherSeries fact0 = new VoucherSeries(); >>                fact0.setSeriesCode( "FREE" ); >>                insert(fact0 ); >> end >> """ >> >> I have verified that all the classes are present in the classloader I >> am passing to the KnowledgeBuilderConfiguration. In fact, I also tried >> creating a MapBasedClassLoader that contains all the missing classes >> so that they can be easily found using fastFindClass. In the code >> listing below, both klass and klass2 resolve to the correct class >> objects. >> >> """ >>            java.util.Properties p = new java.util.Properties(); >>            p.put("drools.dialect.java.compiler", "JANINO"); >>            java.lang.ClassLoader cl = >> java.lang.Class.forName("org.drools.base.extractors.BaseLongClassFieldReader").getClassLoader(); >>            org.drools.rule.CompositeClassLoader compositeClassLoader >> = new org.drools.rule.CompositeClassLoader(cl); >> >>            org.drools.rule.MapBackedClassLoader mbcl = >> getMapBackedClassLoader(cl); >> >>            compositeClassLoader.addClassLoader(mbcl); >>            java.lang.Class klass = >> compositeClassLoader.fastFindClass("rules.Customer"); >>            java.lang.Class klass2 = >> compositeClassLoader.fastFindClass("org.drools.base.extractors.BaseObjectClassFieldReader"); >>            java.lang.ClassLoader finalClassLoader = compositeClassLoader; >> >>            org.drools.builder.KnowledgeBuilderConfiguration kbc = >> org.drools.builder.KnowledgeBuilderFactory.newKnowledgeBuilderConfiguration(p, >> finalClassLoader); >> """ >> >> However, adding the DRL / PKG file, it fails with the exception: >> >> java.lang.NoClassDefFoundError was caught >>  Message="org.drools.base.extractors.BaseObjectClassFieldReader" >>  Source="IKVM.Runtime" >>  StackTrace: >>       at IKVM.NativeCode.java.lang.ClassLoader.defineClass1(Object >> thisClassLoader, String name, Byte[] b, Int32 off, Int32 len, Object >> pd, String source) >>       at java.lang.ClassLoader.defineClass1(String , Byte[] , Int32 , >> Int32 , ProtectionDomain , String ) >>       at java.lang.ClassLoader.defineClass(String name, Byte[] b, >> Int32 off, Int32 len, ProtectionDomain protectionDomain) >>       at org.drools.base.ClassFieldAccessorCache.ByteArrayClassLoader.defineClass(String >> name, Byte[] bytes, ProtectionDomain domain) >>       at org.drools.base.ClassFieldAccessorFactory.getClassFieldReader(Class >> clazz, String fieldName, CacheEntry cache) >>       at org.drools.base.ClassFieldAccessorCache.CacheEntry.getReadAccessor(AccessorKey >> key, Class cls) >>       at org.drools.base.ClassFieldAccessorCache.getReadAcessor(ClassFieldReader >> reader) >>       at org.drools.base.ClassFieldAccessorStore.wire(ClassFieldReader reader) >>       at org.drools.base.ClassFieldAccessorStore.getReader(String >> className, String fieldName, AcceptsReadAccessor target, AccessorType >> accessorType) >>       at org.drools.base.ClassFieldAccessorStore.getReader(String >> className, String fieldName, AcceptsReadAccessor target) >>       at org.drools.rule.builder.PatternBuilder.getFieldReadAccessor(RuleBuildContext >> context, BaseDescr descr, ObjectType objectType, String fieldName, >> AcceptsReadAccessor target, Boolean reportError) >>       at org.drools.rule.builder.PatternBuilder.build(RuleBuildContext >> , Pattern , FieldConstraintDescr , AbstractCompositeConstraint ) >>       at org.drools.rule.builder.PatternBuilder.buildConstraint(RuleBuildContext >> , Pattern , Object , AbstractCompositeConstraint ) >>       at org.drools.rule.builder.PatternBuilder.build(RuleBuildContext >> context, BaseDescr descr, Pattern prefixPattern) >>       at org.drools.rule.builder.PatternBuilder.build(RuleBuildContext >> context, BaseDescr descr) >>       at org.drools.rule.builder.GroupElementBuilder.build(RuleBuildContext >> context, BaseDescr descr, Pattern prefixPattern) >>       at org.drools.rule.builder.RuleBuilder.build(RuleBuildContext context) >>       at org.drools.compiler.PackageBuilder.addRule(RuleDescr ) >>       at org.drools.compiler.PackageBuilder.addPackage(PackageDescr >> packageDescr) >>       at org.drools.compiler.PackageBuilder.addPackageFromDrl(Resource >> resource) >>       at org.drools.compiler.PackageBuilder.addKnowledgeResource(Resource >> resource, ResourceType type, ResourceConfiguration configuration) >>       at org.drools.builder.impl.KnowledgeBuilderImpl.add(Resource >> resource, ResourceType type) >>       at Capillary.Client.RulesEngine.RuleManager.ReadRules(String >> filename) in D:\coderoot\module\DataEntryClient-DVS\SubProjects\RulesEngine\RuleManager.cs:line >> 116 >>  InnerException: >> >> I saw the code at org/drools/base/ClassFieldAccessorCache.java, and it >> seems me that the Reader class for the particular type is being >> defined in situ using a byte[] array, but I am unable to understand >> why it can't load the class at that point. >> >> Can anybody with a better idea of the drools classloading structure >> guide me here? >> >> Also, is the drools.NET project active now? I would post all the steps >> I took for posterity. >> >> Thanks and Regards, >> Krishna. >> >> -- >> http://kpowerinfinity.wordpress.com >> http://www.linkedin.com/in/kpowerinfinity >> _______________________________________________ >> rules-dev mailing list >> rules-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/rules-dev >> > > > > -- > Michael D Neale > home: www.michaelneale.net > blog: michaelneale.blogspot.com > > _______________________________________________ > rules-dev mailing list > rules-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-dev > _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev