Question related to concept of PCK

Hi All.

I am quite a newbie to XI and am only learning it thru online help. I have one conceptual question related to PCK.

My understanding is that PCK is needed by a small business company to communicate to its larger partner which already has XI running. Correct me if I am wrong here itself.

Now if the larger business partner already has XI, why does the smaller one need a PCK at all? The XI instance on the larger partner will have all the necessary adapters to understand any format send by the partner. So even if the partner(smaller) sends any format- be it IDOC/HTTP/FTP, the XI instance on larger partner will have its adapters ready to perform the conversion.

Then why is this PCK needed at all?

Thanks in advance. Hope my query is clear 😊

Regards.

Samant