This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Do you have a WSDL description of the service? It tells you which methods are available for the client to use. Most SOAP toolkits also have a utility that can create client-side code from the WSDL (often called wsdl2java or similar).