SAP web services - Consuming a webservice and surfacing them in SAP for others to use
There are many ways to consume and surface web services with SAP including using the visual composer, SAP Pi and standard ABAP functionality using SE80 and automatially generated ABAP proxys.
SAP VC applications
Creating simple visual composer applications to consume BAPI function modules or external web services (WSDL's)
Consume a Web Service using standard ABAP and SE80
This is a very simple way of consuming a webservice using standard ABAP functionality. It auto generates and ABAP proxy based on a WSDL.
Provide a Web Service using standard ABAP and SE80
This is a very simple way of providing a webservice from SAP to the outside world using standard ABAP functionality. Creates a WSDL from and ABAP function module.