I'm trying to implement the web service in an already established Web application but don't know how to configure my build.xml and another files that I need.
Web services is an
integration technology, not an implementation technology.
So, a web service is not something that
you should attempt to implement into an application. A web service is for enabling communication between two applications.
Application A uses a
Web Service X to communicate with
Application B
Application U uses a
Web Service X to communicate with
Application B
Application M uses a
Web Service X to communicate with
Application B
Application W uses a
Web Service X to communicate with
Application B
So, using the above as an example, the functionality of Application B is exposed via web service. Many applications can communicate with Application B without having a direct syntax-level dependency, or really any technical dependency on the technology of Application B, e.g. platform, OS type, programming language, etc.
Hope this helps.