Web services can be created using two methods: top-down development and bottom-up development. Bottom-up Web services development involves creating a Web service from a Java™ bean or enterprise bean.
Although bottom-up Web service development may be faster and easier, especially if you are new to Web services, the top-down approach is the recommended way of creating a Web service.
When creating a Web service using a bottom-up approach, first you create a Java bean or EJB bean and then use the Web services wizard to create the WSDL file and Web service.