http://www.w3.org/TR/wsdl

Each WSDL document is an XML document whose structure is roughly:

definitions
 documentation
 types (uses XML schema to define data types)
 message (each message is a struct of "parts", parts are defined using the types defined above)
 portType (groups an input message, an output message, and faults)
  different "operations" can be defined based on whether there's an input, an output, or
  both, and the order in which they happen:
   One-way: input only
   Request-response: input, then output
   Solicit-response: output, then input
   Notification: output only
 binding (specifies protocol info, i.e. how (but not where) to access the portType)
 service (a group of ports)
  ports (defines an "endpoint", i.e. where to access a binding)

You can import one wsdl document into another.

-- TobyCabot - 30 Dec 2003