The client-server duality adds a degree of complication to the elegant MVC architecture. Where should the model reside? What about the controller? Traditionally, the model and the controller ran almost entirely on the server, which just pushed the relevant HTML view to the client.
The growth in client-side JavaScript frameworks, such AngularJS, has resulted in a gradual shift to putting more code in the client. Both the controller and a temporary version of the model typically run client-side. The server just functions as a web API: if, for instance, the user updates the model, the controller will send an HTTP request to the server informing it of the change.
It then makes sense to think of the program running server-side and the one running client-side as two separate applications: the server persists data in databases, for instance, and provides a programmatic interface to this data, usually as a web service returning JSON or XML data. The client-side program maintains...
