Good example to communicate between client and server

Hi

Our installers need a good example:

They want to communicate between the client (i3 pro) and server. To write variables to the server (and store there) and to synchronize these variables to the other Connected clients.

For example: to create user-defined clocks (timers/schedules). The end-user on the client change the clock --> the new variable must be stored on the server (where the clocks/timers are running), and syncrhonized to the other clients.

Do you have a good and working example how to realize this?

Thanks

Theo