Creating External Services for BEx Web Applications 
Use
You create an External Service for a BEx Web application based on a master iView. You need not know which master iView is concerned because the master iView is automatically selected.
Procedure
To create an External Service of type BEx Web Application:
The External Service is generated based on the master iView.
You now see the finished External Service and can see which properties it has. If necessary, you can overwrite certain properties of the master iView.
Result
You created an External Service for a BEx Web Application that you can insert directly in a role. Read also
Changing External Services in the Role.