hi,

web service soap interface is defined by a wsdl file.
you can manually write a wsdl file or you can use some tools to generate the same(preferred way).

now, this wsdl file will work as a contract between soap server and soap client .
both server and the client can use this file to generate the stub files wrt soap methods.

I m not sure whether u was asking the same or you have some other doubt!!

Have fun with it!!

Manoj