Resource identification

Resources will be identified in requests. For example, a resource in a web-based REST system will be identified by the URI. And no matter how a resource is stored on the server, it will remain separate from what will be returned to the client in the response.

In fact, resource storage on the server is an implementation but the request and response is what a client is interacting with, so it is like an interface to the client. And a client can identify a resource by this interface. So all that a client knows is what it is requesting and getting in response.

For example, a client usually sends a request to the URI and gets a response in the form of HTML, JSON, or XML. None of these formats are how the server stores data internally in the database or somewhere else on the server. But for a client, it is the URI where it will hit and the HTML, JSON, and XML is what it gets.

This is what a resource is for a client, no matter how it is stored on the server. And this is the benefit, because no matter if the server's internal logic or representation is changed, for the client it will remain the same because the client sends the request to the URI and gets a response in the form of HTML, JSON, or XML and not how it is stored on the server. This constraint, results in loose coupling of resource identification and representation.