This scenario applies to exchanging data with applications located within the organisational data centres and systems and applications hosted in data centres that are owned by vendors or third party suppliers.
The connection to the application / system is secure and the appropriate protocols are in place to link the datacenters together either directly or via a virtual private network link over the internet.
In this case, the systems can be treated as if they are a part of the organisational landscape and the 'internal integration' scenarios apply.
If the network between the hosted application is not secured, then treat the application as an external integration requirement where the appropriate B2B scenarios apply.