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'In computing, a '''stateless protocol''' is a [[communications protocol]] that treats each request as an independent transaction that is unrelated to any previous request so that the communication consists of independent pairs of ''[[request–response|request and response]]''. A stateless protocol does not require the [[server (computing)|server]] to retain [[session (computer science)|session]] information or status about each communications partner for the duration of multiple requests. In contrast, a protocol which requires keeping of the internal state on the [[server (computing)|server]] is known as a [[stateful]] protocol. Examples of stateless protocols include the [[Internet Protocol]] (IP) which is the foundation for the [[Internet]], and the [[Hypertext Transfer Protocol]] (HTTP) which is the foundation of data communication for the [[World Wide Web]]. The stateless design simplifies the server design because there is no need to dynamically allocate storage to deal with conversations in progress. If a client session dies in mid-transaction, no part of the system needs to be responsible for cleaning up the present state of the server. A disadvantage of statelessness is that it may be necessary to include additional information in every request, and this extra information will need to be interpreted by the server. ==Examples== An example of a stateless protocol is [[HTTP]],<ref>{{cite web|url=http://tools.ietf.org/html/rfc7230|title=RFC 7230 - Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing|work=ietf.org|accessdate=20 August 2015}}</ref> meaning that each request message can be understood in isolation. Contrast this with a traditional [[File Transfer Protocol|FTP]] server that conducts an interactive session with the user. During the session, a user is provided a means to be authenticated and set various variables (working directory, transfer mode), all stored on the server as part of the user's state. == Stacking of stateless and stateful protocol layers == There can be complex interactions between stateful and stateless protocols among different protocol layers. For example, HTTP is an example of a stateless protocol layered on top of [[Transmission Control Protocol|TCP]], a stateful protocol, which is layered on top of [[Internet Protocol|IP]], another stateless protocol, which is routed on a network that employs [[BGP]], another stateful protocol, to direct the IP packets riding on the network. This stacking of layers continues even above HTTP. As a work-around for the lack of a session layer in HTTP, [[HTTP server]]s implement various [[Http session#Web server session management|session management]] methods,<ref>{{cite web | accessdate = 2011-04-12 | location = Toronto | work = C cookie bits | title = session management methods reviewed | quote = The following material is intended to introduce the reader to the various techniques that developers have used to implement session tracking on the Web. The main operational characteristics of each method are mentioned in addition to the shortcomings that have been observed in usage. Additional information on session management can be found by searching the Internet. […] | url = http://cookiebits.com/htm/tech.htm }}</ref> typically utilizing a unique identifier in a [[HTTP cookie|cookie]] or parameter that allows the server to track requests originating from the same client, and effectively creating a stateful protocol on top of HTTP. == See also == * [[Soft state]] * [[HATEOAS]] ==References== <references/> *{{FOLDOC}} <!--Interwikies--> <!--Categories--> [[Category:Servers (computing)]] [[Category:Network protocols]] {{network-stub}}'