IETF RFC 7232
Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests
|Publication Date:||1 June 2014|
The Hypertext Transfer Protocol (HTTP) is a stateless applicationlevel protocol for distributed, collaborative, hypertext information systems. This document defines HTTP/1.1 conditional requests, including metadata header fields for indicating state changes, request header fields for making preconditions on such state, and rules for constructing the responses to a conditional request when one or more preconditions evaluate to false.