Hi All Drools 4.0 is using ecj-latest.jar file for jdt core API. apache-tomcat-5.5.17 is using jasper-compiler-jdt.jar file for jdt core API. The CompilationResult class is one of the class in jdt core API. But the jar files are having different versions of CompilationResult class. So we are unable to incorporate Drools 4.0 application with tomcat. please let me know if you have any solution. regards Marimuthu The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com