The following example is from a real application. It's about a hypermarket having the headquarters in one location, one store in the same city, and several stores in other cities.

The hypermarket has an application that uses MSSQL databases in each location. The remote database contains details on stocks and personnel, and needs to replicate with the headquarters database every day at closing hours. Replication is needed for stock details update, as the checkout devices query the database for prices and update stocks so that the headquarters database has all info on daily sales, and available stocks in every store. The application is developed by a third party software company that also does database administration and remote storage; so it needs access to all databases in every store.

All locations have IP Analog Telephone Adapters (IP phones in the diagram that follows) with subscriptions at the main provider (the HQ provider). In this example...