NW Gateway OData for a Function Module using RFC

Hello Experts,

I am trying to create a OData for a Function Module to use it in SAP UI5 front-end. I am very new to Gateway services. The Function Module and the Gateway services are in 2 different ECC systems.

I would appreciate if you could share some in-depth knowledge on how OData is created for Function Module and exposing the data using RFC connection.

Thank you.