When a wireless POS terminal is requesting authorization for a credit/debit card...
Does the wireless terminal communicate to a local/on-site "hub/server" which in-turn acts as a client to communicate with the EFT network's authorization host? (ie, the hub/server acts as the authorization client).
OR does the wireless POS terminal communicate DIRECTLY to the authorization host, via a wireless access point and then across a public/private IP network (ie, the wireless terminal acts as the authorization client).
OR is it sometimes done one way and sometimes the other? And, if so, what are some examples of vendors that use the two topologies?
Mainly, I'm trying to understand where the authorization "client" software is running... on a hub/server on directly or the wireless POS terminal(s). And what are the associated implications on which run-time environments that the client must be able to operate in...