Jack,
Services can be provided as outside In as well as Inside Out (as mentioned in Jitendra's note). Basically there is a Service created for each BAPI/RFC you call.
Best practice would be define the service outside in (Enterprise Service Builder) and the Service Repository is integrated with SAP HR System (in this case) and using SPROXY, proxy class and other objects are created. Inside the proxy method, your BAPI/RFC is called.
+ if ESR is not used, SOAMANAGER is used for End-Point creation and WSDL for SAP as provider and same t.code used to get consumer proxy for 3rd party web services.
Nikhil
