When planning to use a new Web service, you need to learn its interface first. You can learn it from the Web service's WSDL (Web Services Description Language) document. It describes the messages that the Web service understands, the format of its responses to those messages, the protocols that the service support, and so on. The WSDL document is easy to browse. Just click the lines beginning with the ("-") and plus ("+") signs, to contract or expand the code. Here is the WSDL document for a Web service that returns the temperature according to the zip code:
