Introduction to RESTful Web Services

REST is a “Representational state transfer” and it is firstly introduced by Roy Fielding (Fielding is one of the principal authors of the HTTP specification and a co-founder of the Apache HTTP Server project) in his 2000 doctoral dissertation.

REST-style services (i.e., RESTful services) adhere to a set of constraints and architectural principles that include the following:

1.  RESTful services are stateless. As Fielding writes in Section 5.1.3 of his thesis, “each request from client to server must contain all the information necessary to understand the request, and cannot take advantage of any stored context on the server.”
2. RESTful services have a uniform interface. This constraint is usually taken to mean that the only allowed operations are the HTTP operations: GET, POST, PUT, and DELETE.
3. REST-based architectures are built from resources (pieces of information) that are uniquely identified by URIs. For example, in a RESTful purchasing system, each purchase order has a unique URI.
4. REST components manipulate resources by exchanging representations of the resources. For example, a purchase order resource can be represented by an XML document. Within a RESTful purchasing system, a purchase order might be updated by posting an XML document containing the changed purchase order to its URI