How to REST?! - Definitions

What is REST?
Representational State Transfer (REST) is a style of software architecture for distributed hypermedia systems such as the World Wide Web. The term was introduced in the doctoral dissertation in 2000 by Roy Fielding, one of the principal authors of the Hypertext Transfer Protocol (HTTP) specification, and has come into widespread use in the networking community.REST strictly refers to a collection of network architecture principles that outline how resources are defined and addressed. The term is often used in a looser sense to describe any simple interface that transmits domain-specific data over HTTP without an additional messaging layer such as SOAP or session tracking via HTTP cookies.

Principles
REST's proponents argue that the Web enjoyed the scalability and growth that it has had as a direct result of a few key design principles:

• Application state and functionality are divided into resources
  
• Every resource is uniquely addressable using a universal syntax for use in hypermedia links
  
• All resources share a uniform interface for the transfer of state between client and resource, consisting of :
  -A constrained set of well-defined operations
  -A constrained set of content types, optionally supporting code-on-demand
  
• A protocol that is:
  - Client/Server
  - Stateless
  - Cacheable
  - Layered

REST's client-server separation of concerns simplifies component implementation, reduces the complexity of connector semantics, improves the effectiveness of performance tuning, and increases the scalability of pure server components. Layered system constraints allow intermediaries--proxies, gateways, and firewalls--to be introduced at various points in the communication without changing the interfaces between components, thus allowing them to assist in communication translation or improve performance via large-scale, shared caching.
REST enables intermediate processing by constraining messages to be self-descriptive: interaction is stateless between requests, standard methods and media types are used to indicate semantics and exchange information, and responses explicitly indicate cache ability.
—Roy Fielding

REST vs. RPC
A RESTful web application requires a different design approach from an RPC (Remote procedure call) application. An RPC application is exposed as one or more network objects, each with an often unique set of functions that can be invoked. Before a client communicates with the application it must have knowledge of the object identity in order to locate it and must also have knowledge of the object type in order to communicate with it.RESTful design constrains the aspects of a resource that define its interface (the verbs and content types). This leads to the definition of fewer types on the network than an RPC-based application but more resource identifiers (nouns). REST design seeks to define a set of resources that clients can interact with uniformly, and to provide hyperlinks between resources that clients can navigate without requiring knowledge of the whole resource set. Server-provided forms can also be used in a RESTful environment to describe how clients should construct a URL in order to navigate to a particular resource.
—Wikipedia