Web services can be created using two methods: top-down development and bottom-up development. Top-down Web services development involves creating a Web service from a WSDL file.
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 top-down approach, first you design the implementation of the Web service by creating a WSDL file. You can do this using the WSDL Editor. You can then use the Web services wizard to create the Web service and skeleton Java™ classes to which you can add the required code.