Saturday, March 27, 2010

What are RESTful Web Services?

A paper that expands on the basic principles of REST technology can be found at:

The REST architectural style is based on four principles:

Resource identification through URI.

A RESTful Web service exposes a set of resources which identify the targets of the interac- tion with its clients. Resources are identified by URIs [5], which provide a global addressing space for resource and service discov- ery.

Uniform interface.

Resources are manipulated using a fixed set of four create, read, update, delete operations: PUT, GET, POST, and DELETE. PUT creates a new resource, which can be then de- leted using DELETE. GET retrieves the current state of a resource in some representation. POST transfers a new state onto a resource.

Self-descriptive messages.

Resources are decoupled from their representation so that their content can be accessed in a variety of formats (e.g., HTML, XML, plain text, PDF, JPEG, etc.). Meta- data about the resource is available and used, for example, to con- trol caching, detect transmission errors, negotiate the appropriate representation format, and perform authentication or access con- trol.

Stateful interactions through hyperlinks.

Every interaction with a resource is stateless, i.e., request messages are self-contained. Stateful interactions are based on the concept of explicit state trans- fer. Several techniques exist to exchange state, e.g., URI rewriting, cookies, and hidden form fields. State can be embedded in response messages to point to valid future states of the interaction.

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