SimpleOne comprises of the back-end server and front-end server.
Back-end server responsibility is interaction with the database, it handles all the queries received from the frontend server. By results, it forms a JSON object and returns it to a front-end server via API.
The back-end and front-end interaction scheme
The front-end server works as a SPA (Single Page Application). It means that the page is loaded only once, and then, when changed, or when any button clicked, the query to the back-end server is sent to process the changes. The back-end server processes this query and returns the answer in JSON format. After that, the changes are applied and displayed in the interface.