Clearly, we can't have an SPA front end performing an SQL query directly. The HTTP/GQL/REST services are the SPA equivalent of that data source (they are still

Clearly, we can't have an SPA front end performing an SQL query directly. The HTTP/GQL/REST services are the SPA equivalent of that data source (they are still a data source). The C++ and VB apps written back in the day were single user programs so yes that's a difference but not by much architecturally. "Pages" are similarly in SPAs too. We usually have a router that helps the app decide what main "page" is on the screen.