At present, the bottom structure of the retail restaurant chain system is:

Most of them are C/S, and a few are B/S;

Implementation of VPN chain in general branch,

On the lower floor:

C/S is realized by direct data exchange between databases;

In the case of B/S, provide Tomcat service interface through the middle layer, such as Java technology;

Technically, VPN:

1: domain name resolution, free service;

2. Hardware VPN can also be realized;