Hi Swapnil,
With regards to SAP we develop RFC's in SAP ECC and then create a project in Netweaver Gateway in SEGW and we redefine the required services and generate them. The generated URL services is our oData Serivce which we use for UI5/App Development. If you are looking for this details; You learn about this in the following link: Gateway @ Self Paced
If you are want to test them for trial, you can get access Cloud SAP server for free. Refer to the link : SAP Gateway Cloud.
Please suggest what is your back-end server and does it support oData services????
Regards,
Nagesh