Web Services Design Time 
At design time, all objects that are the foundation for Web services are modeled in the Enterprise Services Repository (outside-in mode).
It is also possible in the outside-in mode to make service provider functions available as Web services:
In an AS ABAP service provider system, you can publish independent function modules that were implemented as RFC-enabled function modules, functions groups, or BAPIs as Web services.
All self-contained, modularized functions implemented as Enterprise Java Bean (session bean) or as a Java class in a Web service can be displayed in an AS Java service provider.
The provider proxy is generated and implemented in the service provider system and the service definition is configured. The Web service is then classified and published in the Services Registry.
The service consumer finds the Web service here and generates and implements the consumer proxy in the service consumer system.