Versions involved: IDE: Spring STS 2.3.2.RELEASE Eclipse Drools Plugin: 5.1.1 (Includes JBoss Drools Core, JBoss Drools Guvnor, JBoss Drools Task) Java: JDK 1.6.0_11 Platform: Windows XP 1) Create a sample Drools application using the New Project Wizard and selecting "Drools Project" 2) Name it MyDroolsProject 3) Check all options on the add sample classes (e.g., 'Add a sample HelloWorld rule file to this project', etc.) 4) Check to 'Use default Drools Runtime (currently Drools 5.1.0 runtime)'. Also choose to Generate code compatible with 'Drools 5.1.x'. Click Finish. 5) In your newly created 'MyDroolsProject', drill down to com.sample.DecisionTableTest.java, right click and choose to 'Run As | Java Application' The following stack trace ensues. (Note, yes, I do have the STS Groovy plugin installed) Warning: Cell at E21 not present - adding a blank Build groovy files option has not been set one way or the other: use 'options.put(CompilerOptions.OPTIONG_BuildGroovyFiles, CompilerOptions.ENABLED);' java.lang.NoClassDefFoundError: org/eclipse/core/runtime/Plugin at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:621) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124) at java.net.URLClassLoader.defineClass(URLClassLoader.java:260) at java.net.URLClassLoader.access$000(URLClassLoader.java:56) at java.net.URLClassLoader$1.run(URLClassLoader.java:195) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at org.eclipse.jdt.internal.compiler.Compiler.initializeParser(Compiler.java:755) at org.eclipse.jdt.internal.compiler.Compiler.<init>(Compiler.java:312) at org.eclipse.jdt.internal.compiler.Compiler.<init>(Compiler.java:177) at org.drools.commons.jci.compilers.EclipseJavaCompiler.compile(EclipseJavaCompiler.java:349) at org.drools.commons.jci.compilers.AbstractJavaCompiler.compile(AbstractJavaCompiler.java:51) at org.drools.rule.builder.dialect.java.JavaDialect.compileAll(JavaDialect.java:389) at org.drools.compiler.DialectCompiletimeRegistry.compileAll(DialectCompiletimeRegistry.java:56) at org.drools.compiler.PackageRegistry.compileAll(PackageRegistry.java:74) at org.drools.compiler.PackageBuilder.compileAll(PackageBuilder.java:677) at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:640) at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:254) at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:484) at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:34) at com.sample.DecisionTableTest.readKnowledgeBase(DecisionTableTest.java:44) at com.sample.DecisionTableTest.main(DecisionTableTest.java:25) Caused by: java.lang.ClassNotFoundException: org.eclipse.core.runtime.Plugin at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) ... 27 more -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Drools-Sample-Project... Sent from the Drools - User mailing list archive at Nabble.com.