Portal Integration with XI

Hi Guru's,

Could any one tell me two scenarios where we integrate Portals with the XI system.

If Portal is the receiver/sender then what could be the possible sender/receivers respectively.

Please, also let me know what scenarios (IDOC to HTTP etc) is used for ECC and Portal integration with XI.

What are the Adaptors used for Portals.

Thanks in advance. I will assign points.