# Hyper Text Coffee Pot Control Protocol

The Hyper Text Coffee Pot Control Protocol (HTCPCP) is a facetious communication protocol for controlling, monitoring, and diagnosing coffee pots. It is specified in RFC 2324, published on 1 April 1998 as an April Fools' Day RFC, as part of an April Fools prank. An extension, HTCPCP-TEA, was published as RFC 7168 on 1 April 2014 to support brewing teas, also as an April Fools' Day RFC in error 418.

## Protocol

RFC 2324 was written by Larry Masinter, who describes it as a satire, saying "This has a serious purpose – it identifies many of the ways in which HTTP has been extended inappropriately." The wording of the protocol made it clear that it was not entirely serious; for example, it notes that "there is a strong, dark, rich requirement for a protocol designed espressoly for the brewing of coffee".
Despite the joking nature of its origins, or perhaps because of it, the protocol has remained as a minor presence online. The editor Emacs includes a fully functional client-side implementation of it, and a number of bug reports exist complaining about Mozilla's lack of support for the protocol. Ten years after the publication of HTCPCP, the Web-Controlled Coffee Consortium (WC3) published a first draft of "HTCPCP Vocabulary in RDF" in parody of the World Wide Web Consortium (W3C)'s "HTTP Vocabulary in RDF".
On April 1, 2014, RFC 7168 extended HTCPCP to fully handle teapots.

## Commands and replies

HTCPCP is an extension of HTTP. HTCPCP requests are identified with the Uniform Resource Identifier (URI) scheme coffee (or the corresponding word in any other of the 29 listed languages) and contain several additions to the HTTP methods:
| Method | Definition |
| BREW or POST | Causes the HTCPCP server to brew coffee. Using POST for this purpose is deprecated. A new HTTP request header field, "Accept-Additions", is proposed, supporting optional additions including Cream, Whole-milk, Vanilla, Raspberry, Whisky, Aquavit, etc. |
| GET | "Retrieves" coffee from the HTCPCP server. |
| PROPFIND | Returns metadata about the coffee. |
| WHEN | Says "when", causing the HTCPCP server to stop pouring milk into the coffee (if applicable). |
It also defines four error responses:
| Status code | Definition |
| 406 Not Acceptable | The HTCPCP server is unable to provide the requested addition for some reason; the response should indicate a list of available additions. The RFC observes, "In practice, most automated coffee pots cannot currently provide additions." |
| 408 Request Timeout | The HTCPCP server is unable to make tea for a timeout and forbidden actions. |
| 418 I'm a teapot | The HTCPCP server is a teapot; the resulting entity body "may be short and stout" (a reference to the song "I'm a Little Teapot"). Demonstrations of this behaviour exist. |
| 503 Service Unavailable | According to Mozilla Developer Documentation, "A combined coffee/tea pot that is temporarily out of coffee should instead return 503", when requested to brew. |

## Save 418 movement

On 5 August 2017, Mark Nottingham, chairman of the IETF HTTPBIS Working Group, called for the removal of status code 418 "I'm a teapot" from the Node.js platform, a code implemented in reference to the original 418 "I'm a teapot" established in Hyper Text Coffee Pot Control Protocol. On 6 August 2017, Nottingham requested that references to 418 "I'm a teapot" be removed from the programming language Go and subsequently from Python's Requests and ASP.NET's HttpAbstractions library as well.
In response, 15-year-old developer Shane Brunswick created a website, save418.com, and established the "Save 418 Movement", asserting that references to 418 "I'm a teapot" in different projects serve as "a reminder that the underlying processes of computers are still made by humans". Brunswick's site went viral in the hours following its publishing, garnering thousands of upvotes on the social platform Reddit, and causing the mass adoption of the "#save418" Twitter hashtag he introduced on his site. Heeding the public outcry, Node.js, Go, Python's Requests, and ASP.NET's HttpAbstractions library decided against removing 418 "I'm a teapot" from their respective projects. The unanimous support from the aforementioned projects and the general public prompted Nottingham to begin the process of having 418 marked as a reserved HTTP status code, ensuring that 418 will not be replaced by an official status code for the foreseeable future.
On 5 October 2020, Python 3.9 released with an updated HTTP library including 418 IM_A_TEAPOT status code. In the corresponding pull request, the Save 418 movement was directly cited in support of adoption.

## Usage

The status code 418 is sometimes returned by servers when blocking a request, instead of the more appropriate 403 Forbidden, or 404 Not Found.
Around the time of the 2022 Russian invasion of Ukraine, the Russian military website mil.ru returned the HTTP 418 status code when accessed from outside of Russia as a DDoS attack protection measure. The change was first noticed in December of 2021.