Setting up Drools in Eclipse

Drools version used : 5.5
Eclipse : Luna

Baby steps for setting up Drools 5.5 in Eclipse...

1. Create a Java Project in Eclipse
2. Within src folder, I created folders "java" and "rules" for accommodating the java and .drl file
3. Download the Drools 5.5  jars from Maven 
http://mvnrepository.com/artifact/org.drools/drools-core/5.5.0.Final
4. The following are the jars that are required for making drools work.

xercesImpl.jar

xalan-2.7.1.jar

drools-compiler-5.5.0.Final.jar

drools-core-5.5.0.Final.jar

knowledge-api-5.5.0.Final.jar

mvel2-2.1.3.Final.jar

antlr-runtime-3.3.jar

knowledge-internal-api-5.5.0.Final.jar

slf4j-api-1.6.4.jar

serializer-2.7.1.jar

core-3.2.3.v_686_R32x.jar

xml-apis-1.4.01.jar

xmlbeans-2.6.0.jar

5. Create a user library and include those jars in the java build path

6. Create a drools file named Sample.drl in the rules folder.

7. Create a main class in the java folder, with the following code snippet 

public static void main(String args[]) {

           KnowledgeBase kbase = readKnowledgeBase();

           StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();

           ksession.insert(// Insert the Fact object Here);

                // Define the object that is going to be used as global variable

           Status  status =  new Status();

             // Set the global value

           ksession.setGlobal("status", status);

           ksession.fireAllRules();

           ksession.dispose();
}

 private static KnowledgeBase readKnowledgeBase() throws Exception {
       KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
       kbuilder.add(ResourceFactory.newClassPathResource("Sample.drl"), ResourceType.DRL);
       KnowledgeBuilderErrors errors = kbuilder.getErrors();
       if (errors.size() > 0) {
           for (KnowledgeBuilderError error: errors) {
               System.err.println(error);
           }
           throw new IllegalArgumentException("Could not parse knowledge.");
       }
       KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
       kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
       return kbase;
   }

8. Don't forget to define the required rules in .drl file.

Happy Drooling....