Looking forward, page-57

Probably not relevant to this thread - but I wonder if one of our knowledgeable posters can help me understand how integration works.
If a client wishes to utilize Paydentity for instance, does this mean that the Paydentity program is integrated with the Clients existing platform and then works independently on the Client's server - or is it more like a link back to ISX for processing on their server?
I should perhaps add that calculators, let alone computers, were not even invented when I went to school!
Cheers