Imagine that an application developed decades ago is still in use in a manufacturing factory. Each operator logs in using their own terminal device which does nothing more than capture keyboard input and display characters on its screen. All keyboard input is transmitted to a central computer which decides what actions to take, and in turns instructs the terminal to display certain screens and characters. The terminals are not capable of deciding what actions to take; they rely on the central computer for instructions.

Further imagine the owners of the factory are planning to upgrade the application. When the upgrade is completed, each operator will login to their own desktop computer rather than a terminal device. The application on the desktop computer will decide what screens to display, what to do with the input, and what actions to take as a result.

When the application needs to save its data long term, it will transmit the data to a central computer, which in turn will store it long term. Likewise, when the application needs to recall its long$-$term data, it will request it from the central computer. The central computer does not contain any business logic; it will do nothing more than store and retrieve the client's data upon request.

a$.$ Identify the network architecture used by this application before the upgrade. Explain the mechanics of how this architecture works, including how the four application functions would be divided.

b$.$ Identify what the network architecture of the application would be after the upgrade. Explain the mechanics of how this architecture works, including how the four application functions would be divided.

c$.$ Identify and explain two issues the factory would need to address when switching from the architecture before the upgrade to the architecture after the upgrade.