View source for Hyper Text Coffee Pot Control Protocol

{{Short description|April Fool's joke about facetious communications protocol}}
{{Infobox protocol
| name        = Hyper Text Coffee Pot Control Protocol
| image       = Htcpcp teapot.jpg
| alt         = 
| caption     = [[Frontend and backend|Back-end]] infrastructure of error418.net, which implements HTCPCP using a [[Engineering:Teapot|teapot]] and [[Engineering:Raspberry Pi|Raspberry Pi]]
| standard    = [[Organization:Internet Engineering Task Force|Internet Engineering Task Force]]
| developer   = Larry Masinter
| introdate   = {{Start date|1998|04|01}}
| industry    = <!--industries used (such as PC/Chemical/Multimedia)-->
| connector   = <!--connector(s) usable with protocol-->
| hardware    = <!--examples of compatible hardware-->
| range       = <!--{{convert|X|mi|abbr=on}}-->
| newer       = <!--superseded by which protocol-->
| website     = [https://datatracker.ietf.org/doc/html/rfc2324 rfc2324]
}}
[[File:HTCPCP Pot.jpg|thumb|Working teapot implementing HTCPCP-TEA<ref name=JR />]]
The '''Hyper Text Coffee Pot Control Protocol''' ('''HTCPCP''') is a facetious [[Communication protocol|communication protocol]] for controlling, monitoring, and diagnosing coffee pots. It is specified in {{IETF RFC|2324}}, published on 1 April 1998 as an April Fools' Day RFC,<ref>{{Citation | url = http://tools.ietf.org/html/rfc2324 | title = Network Working Group | date = April 1998 | contribution = Request for Comments 2324 | publisher = [[Organization:Internet Engineering Task Force|IETF]] | access-date = 2012-03-20 | archive-date = 2012-04-04 | archive-url = https://web.archive.org/web/20120404141825/http://tools.ietf.org/html/rfc2324 | url-status = live | last1 = Masinter | first1 = Larry M. }}</ref> as part of an April Fools prank.<ref>{{Cite book |last=DeNardis |first=Laura |url={{google books|plainurl=yes|id=Secqz0XQJIsC|pg=PA27}} |title=Protocol Politics: The Globalization of Internet Governance |date=30 September 2009 |publisher=MIT Press |isbn=978-0-262-04257-4 |pages=27ff |access-date=8 May 2012}}</ref> An extension, HTCPCP-TEA, was published as RFC 7168 on 1 April 2014<ref name=rfc7168>{{Citation | url = https://tools.ietf.org/html/rfc7168 | title = The Hyper Text Coffee Pot Control Protocol for Tea Efflux Appliances (HTCPCP-TEA) | date = April 2014 | contribution = Request for Comments 7168 | publisher = [[Organization:Internet Engineering Task Force|IETF]] | access-date = 2014-04-22 | archive-date = 2014-05-29 | archive-url = https://web.archive.org/web/20140529225719/http://tools.ietf.org/html/rfc7168 | url-status = live | last1 = Nazar | first1 = Imran }}</ref> to support brewing teas, which is also an April Fools' Day RFC.

==Protocol==
RFC 2324 was written by Larry Masinter, who describes it as a satire, saying "This has a serious purpose &ndash; it identifies many of the ways in which [[HTTP]] has been extended inappropriately."<ref>{{Cite web |last=Masinter |first=Larry  |title=IETF RFCs |url=http://larry.masinter.net |url-status=dead |archive-url=https://web.archive.org/web/20130327202242/http://larry.masinter.net/ |archive-date=2013-03-27}}</ref> 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 {{Sic}} 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 [[Software:Emacs|Emacs]] includes a fully functional client side implementation of it,<ref>{{Citation | title = Emarsden | url = http://emarsden.chez.com/downloads/ | publisher = Chez | contribution = Emacs extension: coffee.el | access-date = 2009-02-10 | archive-date = 2009-02-01 | archive-url = https://web.archive.org/web/20090201001552/http://emarsden.chez.com/downloads/ | url-status = live }}.</ref> and a number of bug reports exist complaining about Mozilla's lack of support for the protocol.<ref>{{Citation|title=Bug 46647 – (coffeehandler) HTCPCP not supported (RFC2324)|url=https://bugzilla.mozilla.org/show_bug.cgi?id=46647|work=Bugzilla|publisher=Mozilla|access-date=2005-12-21|archive-date=2011-05-14|archive-url=https://web.archive.org/web/20110514065147/https://bugzilla.mozilla.org/show_bug.cgi?id=46647|url-status=live}}</ref> Ten years after the publication of HTCPCP, the ''Web-Controlled Coffee Consortium'' (''WC3'') published a first draft of "HTCPCP Vocabulary in [[Resource Description Framework|RDF]]"<ref>{{Citation |title=HTCPCP Vocabulary in RDF – WC3 RFC Draft |date=1 April 2008 |url=https://cstrobbe.gitlab.io/WC3/TR/2008/RFC-htcpcp-in-rdf-20080401/ |publisher=Chief Arabica (Web-Controlled Coffee Consortium) |access-date=17 March 2023 |via=github |archive-date=15 May 2021 |archive-url=https://web.archive.org/web/20210515041835/https://cstrobbe.github.io/WC3/TR/2008/RFC-htcpcp-in-rdf-20080401/ |url-status=live }}</ref> in parody of the [[Organization:World Wide Web Consortium|World Wide Web Consortium]]'s (W3C) "HTTP Vocabulary in RDF".<ref>{{Citation | editor-first = Johannes | editor-last = Koch | others = et al | url = http://www.w3.org/TR/HTTP-in-RDF/ | title = HTTP Vocabulary in RDF | publisher = [[Organization:World Wide Web Consortium|W3]] | access-date = 17 August 2009 | archive-date = 15 October 2009 | archive-url = https://web.archive.org/web/20091015080216/http://www.w3.org/TR/HTTP-in-RDF/ | url-status = live }}</ref>

On April 1, 2014, RFC 7168 extended HTCPCP to fully handle teapots.<ref name=rfc7168 />

==Commands and replies==
HTCPCP is an extension of [[Hypertext Transfer Protocol|HTTP]]. HTCPCP requests are identified with the [[Uniform Resource Identifier]] (URI) scheme <code>coffee</code> (or the corresponding word in any other of the 29 listed languages) and contain several additions to the HTTP methods:
{| class="wikitable"
! Method !! Definition
|-
|valign=top|<code>BREW</code> or <code>POST</code>||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.
|- valign=top
|<code>GET</code>||"Retrieves" coffee from the HTCPCP server.
|- valign=top
|<code>PROPFIND</code>||Returns [[Metadata|metadata]] about the coffee.
|- valign=top
|<code>WHEN</code>||Says "when", causing the HTCPCP server to stop pouring milk into the coffee (if applicable).
|}

It also defines three error responses:
{| class="wikitable"
! Status code !! Definition
|-
|valign=top|<code>{{nowrap|406 Not Acceptable}}</code>||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 that "In practice, most automated coffee pots cannot currently provide additions."
|- valign=top
|<code>{{nowrap|418 I'm a teapot}}</code>||The HTCPCP server is a [[Engineering:Teapot|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.<ref name="JR">{{Citation |last=Reddington |first=Joseph |title=Illustrated implementation of Error 418 |url=http://joereddington.com/projects/418-error-code-teapot/ |archive-url=https://web.archive.org/web/20150906071854/http://joereddington.com/projects/418-error-code-teapot/ |access-date=2014-10-18 |archive-date=2015-09-06 |url-status=dead}}</ref><ref>{{Cite web |url=http://www.qdh.org.uk/wordpress/?p=546 |title=A Goblin Teasmade teamaker with an implementation of Error 418 |access-date=2014-07-26 |archive-url=https://web.archive.org/web/20141206053112/http://www.qdh.org.uk/wordpress/?p=546 |archive-date=2014-12-06 |url-status=dead }}</ref>
|-
|<code>{{nowrap|503 Service Unavailable}}</code>
|According to Mozilla Developer Documentation "A combined coffee/tea pot that is temporarily out of coffee should instead return 503", when requested to brew<ref>{{Cite web |date=2023-04-10 |title=418 I'm a teapot - HTTP {{!}} MDN |url=https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/418 |access-date=2023-09-21 |website=developer.mozilla.org |language=en-US}}</ref>
|}

==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 [[Software:Node.js|Node.js]] platform, a code implemented in reference to the original 418 "I'm a teapot" established in Hyper Text Coffee Pot Control Protocol.<ref>{{Cite web |last=Nottingham |first=Mark |title=418 I'm A Teapot #14644 |url=https://github.com/nodejs/node/issues/14644#issue-248218948 |via=github |access-date=2017-08-12 |archive-date=2017-08-10 |archive-url=https://web.archive.org/web/20170810220743/https://github.com/nodejs/node/issues/14644#issue-248218948 |url-status=live }}</ref> On 6 August 2017, Nottingham requested that references to 418 "I'm a teapot" be removed from the programming language [[Go (programming language)|Go]]<ref>{{Cite web |last=Nottingham |first=Mark |title=net/http: remove support for status code 418 I'm a Teapot |url=https://github.com/golang/go/issues/21326#issue-248234750 |via=github |access-date=2017-08-12 |archive-date=2017-08-10 |archive-url=https://web.archive.org/web/20170810220643/https://github.com/golang/go/issues/21326#issue-248234750 |url-status=live }}</ref> and subsequently from [[Python (programming language)|Python]]'s [[Software:Requests|Requests]]<ref>{{Cite web |last=Nottingham |first=Mark |title=418 418 I'm a Teapot #4238 |url=https://github.com/requests/requests/issues/4238#issue-249497185 |via=github |access-date=2017-08-12 |archive-date=2021-05-15 |archive-url=https://web.archive.org/web/20210515041837/https://github.com/psf/requests/issues/4238#issue-249497185 |url-status=live }}</ref> and [[Software:ASP.NET|ASP.NET]]'s HttpAbstractions library<ref>{{Cite web |last=Nottingham |first=Mark |title=418 I'm a Teapot #915 |url=https://github.com/aspnet/HttpAbstractions/issues/915 |via=github |access-date=2017-08-12 |archive-date=2019-05-10 |archive-url=https://web.archive.org/web/20190510155446/https://github.com/aspnet/HttpAbstractions/issues/915 |url-status=live }}</ref> as well.

In response, 15-year-old developer Shane Brunswick created a website, save418.com,<ref>{{Cite web |last=Brunswick |first=Shane |title=We are the teapots |url=http://save418.com |website=The Save 418 Movement |date=2017-09-10 |access-date=2021-05-15 |archive-date=2021-05-15 |archive-url=https://web.archive.org/web/20210515041851/https://save418.com/ |url-status=live }}</ref> 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 [[Company:Reddit|Reddit]],<ref>{{Cite web |title=HTTP Error Code 418 I'm a Teapot is about to be removed from Node. We've gotta do something. [x-post /r/webdev] |url=https://www.reddit.com/r/programming/comments/6sxea0/http_error_code_418_im_a_teapot_is_about_to_be/ |via=reddit |access-date=2017-08-12 |archive-date=2017-08-11 |archive-url=https://web.archive.org/web/20170811223038/https://www.reddit.com/r/programming/comments/6sxea0/http_error_code_418_im_a_teapot_is_about_to_be/ |url-status=live }}</ref> and causing the mass adoption of the "#save418" [[Company:Twitter|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,<ref>{{Cite web |last=Nottingham |first=Mark |title=Reserving 418 |url=https://lists.w3.org/Archives/Public/ietf-http-wg/2017JulSep/0332.html |via=github |access-date=2017-08-12 |archive-date=2017-08-13 |archive-url=https://web.archive.org/web/20170813012814/https://lists.w3.org/Archives/Public/ietf-http-wg/2017JulSep/0332.html |url-status=live }}</ref> 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 <code>418 IM_A_TEAPOT</code> status code.<ref>{{Cite web|date=2020-10-05|title=What's New In Python 3.9 — Python 3.9.0 documentation|url=https://docs.python.org/3/whatsnew/3.9.html#http|access-date=2020-10-08|website=Python Documentation|archive-date=2020-10-07|archive-url=https://web.archive.org/web/20201007172936/https://docs.python.org/3/whatsnew/3.9.html#http|url-status=live}}</ref> In the corresponding pull request, the Save 418 movement was directly cited in support of adoption.<ref>{{Cite web|title=Issue 39507: http library missing HTTP status code 418 "I'm a teapot" – Python tracker|url=https://bugs.python.org/issue39507#msg361134|access-date=2020-10-08|website=bugs.python.org|archive-date=2020-10-14|archive-url=https://web.archive.org/web/20201014070511/https://bugs.python.org/issue39507#msg361134|url-status=live}}</ref>

== Usage ==
The status code 418 is sometimes returned by servers when blocking a request, instead of the more appropriate [[HTTP 403|403 Forbidden]].<ref>{{cite web|url=https://help.dreamhost.com/hc/en-us/articles/215947927-Enable-extra-web-security-on-a-website|title=Enable extra web security on a website|access-date=2022-12-18|website=[[Company:DreamHost|DreamHost]]|language=en}}</ref> 

Around the time of the 2021–2022 Russo-Ukrainian crisis, the Russian military website mil.ru returned the HTTP 418 status code when accessed from outside of Russia as a [[Denial-of-service attack|DDoS attack]] protection measure.<ref>{{Cite web |date=2022-02-25 |title=Russia appears to deploy digital defenses after DDoS attacks |url=https://therecord.media/russia-appears-to-deploy-digital-defenses-after-ddos-attacks/ |access-date=2022-02-26 |website=The Record by Recorded Future |language=en}}</ref><ref>{{Cite web |title=I Went to a Russian Website and All I Got Was This Lousy Teapot |url=https://www.pcmag.com/news/i-went-to-a-russian-website-and-all-i-got-was-this-lousy-teapot |access-date=2022-02-28 |website=PCMag |language=en}}</ref> The change was first noticed in December of 2021.<ref>{{cite web | url=https://news.ycombinator.com/item?id=29594249 | title=Russian MoD website blocked for non-Russian IPs &#124; Hacker News }}</ref><!-- use https://cheapskatesguide.org/articles/kiwifarms.html or something better -->

==See also==
* [[Social:Trojan Room coffee pot|Trojan Room coffee pot]]
* [[Internet of things]]
* {{section link|List of HTTP status codes|4xx client errors}}

== References ==
{{Reflist|colwidth=30em}}

==External links==
* [https://www.google.com/teapot Google's demo page: Error 418 (I'm a teapot)!?]
* [https://godoc.org/github.com/davsk/teapot Package teapot HTCPCP-TEA implementation] by David Skinner
* [https://save418.com/ save418.com]
* [http://www.error418.net/ error418.net] {{Webarchive|url=https://web.archive.org/web/20210107214915/http://www.error418.net/ |date=2021-01-07 }}

{{IETF RFC 1st april}}
{{URI scheme}}
{{Error messages}}

[[Category:Application layer protocols]]
[[Category:Computer errors]]

{{Sourceattribution|Hyper Text Coffee Pot Control Protocol}}