Beginning with client-server

The client-server architecture or model helps in the separation of concerns between the user interface and data storage:

Let's discuss the client and server in the context of ROA as follows:

• Client: It is the component that is the requestor of a service and sends requests for various types of services to the server
• Server: It is the component that is the service provider and continuously provides services to the client as per the requests 

Clients and servers typically comprise distributed systems that communicate over a network.