Hi,
I wrote a little tutorial explaining how to execute remote-enabled function modules (RFMs) from within a Java application running on the NetWeaver Cloud:
Executing RFC Calls from a NetWeaver Cloud Application
Currently the SAP Cloud Connector does not yet support the RFC protocol, but with the workaround described in the above document, it should be possible to call any ABAP function module in an on-premise R/3 system in a secure and effortless way. The workaround leverages an internally installed SAP Business Connector, which can be set up in half an hour, if not yet installed.
The above mechanism is not limited to calling RFMs: the Business Connector provides much more functionality, and the referenced jar file allows executing any SAP BC Service very easily, so you could for example access an on-premise database using the Business Connector's WmDB package, put/get files onto/from an internal FTP server, etc.
In this thread please report your experiences with the above procedure or any problems you encounter.
Ulrich