Give me an example of real web service?
One example of web services is IBM Web Services browser. You can get it from IBM Alphaworks site. This browser shows various demos related to web services. Basically web services can be used with the help of SOAP, WSDL, and UDDI. All these, provide a plug-and-play interface for using web services such as stock-quote service, a traffic-report service, weather service etc.
