Calling Non SAP External REST API from ABAP Program

Hello Experts,

We have a requirement to call a Non SAP External REST API's (Create, Update) from SAP system using ABAP program/Function Module to send SAP data. REST API (Create and Update) will be created by external system and we have to send SAP data by calling the API's. I am going through the information in different threads and blogs but wanted a simpler solution as the project time is short. Need your help on what is the best approach. Can you also suggest what is the best and secure approach when sending data from SAP system. 

Thanks

Ravi