When is the connector suitable and at what point do I need the server?
This is a graphic of what im thinking to do:
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I don't know about "Ciao" but generally a rest server answers requests from a client that is connecting via a rest connector. You client will use POST, GET, PUT, etc. to ask the server to provide a service. This could be as simple as "GET .\index.htm" or more likely posting information to be stored in a database.
The server will sit waiting for these requests and will have handling routines for each specific request and might supply a response.