Provide Rest Web Service

Hi,

We are trying to integrate an External system directly to Cloud for Customer but our preference would be on using REST web service without using HCI or PI. The call/initiation should come from the external system since it would provide the initial data ( i.e. leads, contacts) to be used in C4C. Unfortunately, I haven't seen any guides or function for this. Current options I can see are:

- C4C initiates the REST webservice (using WebServiceUtilities in Cloud App Studio) to an external system

- External System using SOAP webservice to initiate the update/creation of data in C4C.

Is there a way where we can use REST webservice from an external system to update C4C directly?

Regards,

Jeffry