As I already mentioned, in a REST-based application, everything including static resources, data, and operations is considered as a resource and identified by a URI. For example, consider a piece of functionality to add a new product to our store; we can represent that operation by a URI, something such as http://localhost:8080/webstore/products/add, and we can pass the new product details in XML or JSON representation to that URL. So, in REST, URIs are used to connect clients and servers to exchange resources in the form of representations (HTML, XML, JSON, and so on). In order to exchange data, REST relies on basic HTTP protocol methods GET, POST, PUT, and DELETE.

Spring provides extensive support for developing REST-based web services. In our previous chapters, we have seen that, whenever a web request comes in, we returned a web page to serve that request; usually that web page contained some states (that is, dynamic data). However, in REST-based applications, we...