The Database Server(s) contain all the configuration data, tables and business data that needs to be persisted in order to generate invoices, and rate and charge usage information.
The database is highly secured and access to the data is only allowed via a direct connection from the secured Application Subnet.
External access to data can only be gained through the provided RESTFul API served up by the Web Subnet which is authenticated with a JWT token. That Web Subnet processes the JWT authenticated RESTful request and then communicates with the authenticated Application Server Subnet which then in turn is authenticated by, and retrieves data from, the Data Subnet. This provides multiple layers of security and authentication for any kind of data retrieval.
Depending on your business needs different database deployment models are possible which are described in our Deployment Architecture section .