I have little confusion about implementing serializable for a result class in "Building J2EE Application Quickstart" (TraderX Example). The class TraderResult is implementing serializable and one of its property "message" that is holding a message is being displayed in JSP, whereas in some other Web project examples,the class whose properties are being displayed in JSP, are not implementing Serializable,so whats the difference?

Can you give an example of the other web projects samples?

Also, you need to serialize anything that might be persisted. This includes anything that might be persisted to the disk by the app server (saving session state) or any reasource that can be duplicated across a cluster.