A Web Service control makes it easy to access an external web service from a WebLogic Workshop application. You can create a Web Service control for any web service that publishes a WSDL (Web Service Definition Language) file. A WSDL file describes the methods and callbacks that a web service implements, including method names, parameters, and return types. It also describes the protocols that a web service supports. To learn more about WSDL files, see WSDL Files: Web Service Descriptions.
Note: You should not use a Web Service control to invoke a web service that resides in the same application. Invoking a web service via a Web Service control means marshalling the method parameters into a SOAP message on the calling end and unmarshalling the SOAP message on the receiving end, then again for the method return value. This is very inefficient when the invocation is local. You would usually be tempted to invoke one web service from another if the called web service included business logic you want to access from the calling web service.
In general, you should place business logic in custom Java controls instead of in web services. This allows you to access the business logic from various contexts in the application (web services, other controls, page flows) without incurring the cost of data marshalling and unmarshalling. Web Service controls should only be used to invoke web services that are truly external to your application.