More recently, REpresentational State Transfer (RESTful) Web services have been regaining popularity, particularly with Internet companies. These also meet the W3C definition, and are often better integrated with Hypertext Transfer Protocol (HTTP) than SOAP-based services. They do not require XML messages or WSDL service-API definitions.
"REST" redirects here. For other uses, see Rest.
Representational state transfer (REST) is a style of software architecture for distributed hypermedia systems such as the World Wide Web. As such, it is not strictly a method for building "web services." The terms "representational state transfer" and "REST" were introduced in 2000 in the doctoral dissertation of Roy Fielding, one of the principal authors of the Hypertext Transfer Protocol (HTTP) specification.
REST refers in the strictest sense to a collection of network architecture principles which outline how resources are defined and addressed. The term is often used more loosely to describe any simple interface which transmits domain-specific data over HTTP without an additional messaging layer such as SOAP or session tracking via HTTP cookies. These two meanings can conflict as well as overlap. It is possible to design a software system in accordance with Fielding's REST architectural style without using HTTP and without interacting with the World Wide Web. It is also possible to design simple XML+HTTP interfaces which do not conform to REST principles, and instead follow a model of remote procedure call. The difference between the uses of the term "REST" therefore causes some confusion in technical discussions.
Systems which follow Fielding's REST principles are often referred to as "RESTful".