Hi Vidya,
On ECC/ABAP side related to PI, you should know about following things,
- RFC (Remote Enable Function Module)
- Idoc (Intermediate Document)
- ABAP Proxies
etc.
You can refer to this link for further information Important URLs, Transaction Codes, ABAP Reports in Process Integration 7.1 - Process Integration - SCN Wiki
Regards,
Dipen.