Hi Yue:
Thanks for posting the question. Here is the guidance I received from Rob Jones with the Ariba team:
"Goods Receipt Notification (GRN) is supported in the Network, however it is up to the buyer as to whether or not they have implemented this document in their transaction set. If they have, then suppliers could* be able to see the GRN information in the Network related to Goods that have shipped; however, if the buyer organization has not implemented the GRN, the supplier will definitely not be able to view receipt information via the Network.
*Buyer organizations control what information is sent from their back-office system to the Network. In many cases the information will be available to the suppliers if the buyer organization has implemented the GRN document in their connection to the Network, however there are some cases where buyers limit the use of some document types in the Network to specific business units within their organization which may result in GRN data not being sent to some suppliers."
Debbie Curtis-Magley
Ariba Exchange Community Manager