Roy Thomas Fielding (born 1965) is an American computer scientist, one of the principal authors of the HTTP specification and the originator of the Representational State Transfer (REST) architectural style. He is an authority on computer network architecture and co-founded the Apache HTTP Server project.
38-480: Do Not Track ( DNT ) is a formerly official HTTP header field , designed to allow internet users to opt out of tracking by websites —which includes the collection of data regarding a user's activity across multiple distinct contexts, and the retention, use, or sharing of data derived from that activity outside the context in which it occurred. The Do Not Track header was originally proposed in 2009 by researchers Christopher Soghoian and Sid Stamm. Mozilla Firefox became
76-672: A binary protocol , where headers are encoded in a single HEADERS and zero or more CONTINUATION frames using HPACK (HTTP/2) or QPACK (HTTP/3), which both provide efficient header compression. The request or response line from HTTP/1 has also been replaced by several pseudo-header fields, each beginning with a colon ( : ). A core set of fields is standardized by the Internet Engineering Task Force (IETF) in RFC 9110 and 9111 . The Field Names , Header Fields and Repository of Provisional Registrations are maintained by
114-509: A carriage return (CR) and line feed (LF) character sequence. The end of the header section is indicated by an empty field line, resulting in the transmission of two consecutive CR-LF pairs. In the past, long lines could be folded into multiple lines; continuation lines are indicated by the presence of a space (SP) or horizontal tab (HT) as the first character on the next line. This folding was deprecated in RFC 7230. HTTP/2 and HTTP/3 instead use
152-567: A Do Not Track list for online advertising. The proposal would have required that online advertisers submit their information to the FTC, which would compile a machine-readable list of the domain names used by those companies to place cookies or otherwise track consumers. In July 2009, researchers Christopher Soghoian and Sid Stamm implemented support for the Do Not Track header in the Firefox web browser via
190-490: A Do Not Track option is enabled by default for Internet Explorer 10 and Windows 8 . Microsoft faced criticism for its decision to enable Do Not Track by default from advertising companies, who say that use of the Do Not Track header should be a choice made by the user and must not be automatically enabled. The companies also said that this decision would violate the Digital Advertising Alliance 's agreement with
228-491: A Do Not Track solution, via a browser header. Microsoft's Internet Explorer 9 , Apple's Safari, Opera and Google Chrome all later added support for the header approach. In August 2015 a coalition of privacy groups led by the Electronic Frontier Foundation using W3C 's Tracking Preference Expression (DNT) standard proposed that "Do not track" be the goal for advocates to demand of businesses. In January 2019,
266-480: A best effort not to write it to disk (i.e not to cache it). The request that a resource should not be cached is no guarantee that it will not be written to disk. In particular, the HTTP/1.1 definition draws a distinction between history stores and caches. If the user navigates back to a previous page a browser may still show you a page that has been stored on disk in the history store. This is correct behavior according to
304-423: A browser or proxy to not use the cache contents merely based on "freshness criteria" of the cache content. Another common way to prevent old content from being shown to the user without validation is Cache-Control: max-age=0 . This instructs the user agent that the content is stale and should be validated before use. The header field Cache-Control: no-store is intended to instruct a browser application to make
342-544: A key architectural principle of the World Wide Web and received a large amount of attention. Computer engineers frequently hold up REST as an approach to developing web services , as an alternative to other distributed-computing specifications such as SOAP . Fielding has also been heavily involved in the development of HTML and Uniform Resource Identifiers . Fielding co-founded the Apache HTTP Server project and
380-497: A patch to the source code of the Apache HTTP Server , which would make the server explicitly ignore any use of the Do Not Track header by users of Internet Explorer 10. Fielding wrote that Microsoft's decision "deliberately violates" the Do Not Track specification because it "does not protect anyone's privacy unless the recipients believe it was set by a real human being, with a real preference for privacy over personalization". The Do Not Track specification did not explicitly mandate that
418-834: A prototype add-on. Stamm was, at the time, a privacy engineer at Mozilla, while Soghoian soon afterward started working at the FTC. One year later, during a U.S. Senate privacy hearing, FTC Chairman Jon Leibowitz told the Senate Commerce Committee that the commission was exploring the idea of proposing a "do-not-track" list. In December 2010, the FTC issued a privacy report that called for a "do-not-track" system that would enable people to avoid having their actions being monitored online. One week later, Microsoft announced that its next browser would include support for Tracking Protection Lists that block tracking of consumers using blacklists supplied by third parties. In January 2011, Mozilla announced that its Firefox browser would soon provide
SECTION 10
#1732894665458456-400: A time earlier than the response time. Notice that no-cache is not instructing the browser or proxies about whether or not to cache the content. It just tells the browser and proxies to validate the cache content with the server before using it (this is done by using If-Modified-Since, If-Unmodified-Since, If-Match, If-None-Match attributes mentioned above). Sending a no-cache value thus instructs
494-498: A web server responds with Cache-Control: no-cache then a web browser or other caching system (intermediate proxies) must not use the response to satisfy subsequent requests without first checking with the originating server (this process is called validation). This header field is part of HTTP version 1.1, and is ignored by some caches and browsers. It may be simulated by setting the Expires HTTP version 1.0 header field value to
532-550: A weight to use in content negotiation . For example, a browser may indicate that it accepts information in German or English, with German as preferred by setting the q value for de higher than that of en , as follows: Accept-Language: de; q=1.0, en; q=0.5 The standard imposes no limits to the size of each header field name or value, or to the number of fields. However, most servers, clients, and proxy software impose some limits for practical and security reasons. For example,
570-708: Is licensed in a way that permits reuse under the Creative Commons Attribution-ShareAlike 3.0 Unported License , but not under the GFDL . All relevant terms must be followed. Roy Fielding Fielding works as a Senior Principal Scientist at Adobe Systems in San Jose, California . Fielding was born in 1965 in Laguna Beach, California . He describes himself as "part Maori , Kiwi , Yank, Irish, Scottish, British, and California beach bum". In 1999,
608-605: Is supported by Firefox creator, Mozilla as well as the California Attorney General . Notably, Google Chrome has not yet implemented the signal, despite still allowing users to enable the now depreciated Do Not Track header. However, there are third-party extensions available for Chrome if users want to send the GPC header with their requests, including the Privacy Badger extension by The Electronic Frontier Foundation ,
646-518: Is the X-REQUEST-ID http header?" , authored by Stefan Kögl at Stack Exchange, which is licensed in a way that permits reuse under the Creative Commons Attribution-ShareAlike 3.0 Unported License , but not under the GFDL . All relevant terms must be followed. As of this edit , this article uses content from "Why does ASP.NET framework add the 'X-Powered-By:ASP.NET' HTTP Header in responses?" , authored by Adrian Grigore at Stack Exchange, which
684-614: The DuckDuckGo Privacy Essentials add-on, and more. One key difference between the Do Not Track header and GPC is that GPC is a valid do-not-sell-my-personal-information signal according to the California Consumer Privacy Act (CCPA), which stipulates that websites are legally required to respect a signal sent by users who want to opt-out of having their personal data sold. In July 2021, the California Attorney General clarified through an FAQ that under law,
722-460: The IANA . Additional field names and permissible values may be defined by each application. Header field names are case-insensitive. This is in contrast to HTTP method names (GET, POST, etc.), which are case-sensitive. HTTP/2 makes some restrictions on specific header fields (see below). Non-standard header fields were conventionally marked by prefixing the field name with X- but this convention
760-568: The Massachusetts Institute of Technology (MIT) Technology Review TR100 named him one of the top 100 innovators in the world under the age of 35. In 2000, he received his doctorate from the University of California, Irvine . Architectural Styles and the Design of Network-based Software Architectures , Fielding's doctoral dissertation, describes Representational State Transfer (REST) as
798-545: The end-user and are only processed or logged by the server and client applications. They define how information sent/received through the connection are encoded (as in Content-Encoding ), the session verification and identification of the client (as in browser cookies , IP address, user-agent ) or their anonymity thereof (VPN or proxy masking, user-agent spoofing), how the server should handle data (as in Do-Not-Track ),
SECTION 20
#1732894665458836-1059: The Apache 2.3 server by default limits the size of each field to 8,190 bytes, and there can be at most 100 header fields in a single request. Must not be used with HTTP/2. Connection: Upgrade Mandatory since HTTP/1.1. If the request is generated directly in HTTP/2, it should not be used. Host: en.wikipedia.org Only trailers is supported in HTTP/2. Must not be used with HTTP/2. Must not be used in HTTP/2. DNT: 0 (Do Not Track Disabled) X-Forwarded-For: 129.78.138.66, 129.78.64.103 X-Forwarded-Host: en.wikipedia.org Must not be used with HTTP/2. X-Correlation-ID, Correlation-ID When using HTTP/2, servers should instead send an ALTSVC frame. Must not be used with HTTP/2. Permanent Must not be used with HTTP/2. Must not be used in HTTP/2 Timing-Allow-Origin: <origin>[, <origin>]* If
874-568: The European Union's General Data Protection Regulation (GDPR) have imposed restrictions on how companies are to store and process personal information. Princeton University associate professor of computer science Jonathan Mayer , who was a member of the W3C's working group for DNT, argued that the concept is a "failed experiment". Global Privacy Control (GPC) is a proposed HTTP header field and DOM property that can be used to inform websites of
912-539: The Global Privacy Control signal must be honored. On August 24, 2022, the California Attorney General announced Sephora paid a $ 1.2-million settlement for allegedly failing to process opt-out requests via a user-enabled global privacy control signal. List of HTTP header fields HTTP header fields are a list of strings sent and received by both the client program and server on every HTTP request and response. These headers are usually invisible to
950-425: The HTTP/1.0 spec, has the same purpose. It, however, is only defined for the request header. Its meaning in a response header is not specified. The behavior of Pragma: no-cache in a response is implementation specific. While some user agents do pay attention to this field in responses, the HTTP/1.1 RFC specifically warns against relying on this behavior. As of this edit , this article uses content from "What
988-400: The U.S. government to honor a Do Not Track system, because the coalition said it would only honor such a system if it were not enabled by default by web browsers. A Microsoft spokesperson defended its decision however, stating that users would prefer a web browser that automatically respected their privacy. On September 7, 2012, Roy Fielding , an author of the Do Not Track standard, committed
1026-497: The W3C Tracking Protection Working Group was disbanded, citing "insufficient deployment of these extensions" and lack of "indications of planned support among user agents, third parties, and the ecosystem at large". Beginning the following month, Apple removed DNT support from Safari, citing that it could be used as a " fingerprinting variable" for tracking. When using the "Express" settings upon installation,
1064-407: The age (the time it has resided in a shared cache ) of the document being downloaded, amongst others. In HTTP version 1.x, header fields are transmitted after the request line (in case of a request HTTP message) or the response line (in case of a response HTTP message), which is the first line of a message. Header fields are colon-separated key-value pairs in clear-text string format, terminated by
1102-574: The definition of "user-enabled global privacy controls" defined by the California Consumer Privacy Act (CCPA) and the European General Data Protection Regulation (GDPR). In this case, the new header would be automatically strengthened by existing laws and companies would be required to honor it. The DNT header accepts three values: 1 in case the user does not want to be tracked (opt-out) , 0 in case
1140-512: The first browser to implement the feature. The header failed to find widespread success due to the lack of legislation requiring companies to legally respect the Do Not Track header; and most companies and websites not respecting the header when sent by the user. In 2020, a coalition of US-based internet companies announced the Global Privacy Control header that succeeds Do Not Track header. The creators hope that this new header will meet
1178-883: The header. Websites that honor DNT requests include Medium and Pinterest . Despite offering the option in its Chrome web browser, Google did not implement support for DNT on its websites, and directed users to its online privacy settings and opt-outs for interest-based advertising instead. The Digital Advertising Alliance , Council of Better Business Bureaus and the Data & Marketing Association does not require its members to honor DNT signals. Use of ad blocking software to block web trackers and advertising has become increasingly common (with users citing both privacy concerns and performance impact as justification), while Apple and Mozilla began to add privacy enhancements (such as "tracking protection") to their browsers, that are designed to reduce undue cross-site tracking. In addition, laws such as
Do Not Track - Misplaced Pages Continue
1216-460: The specification and no longer automatically enable Do Not Track as part of the operating system's "Express" default settings, but that the company will "provide customers with clear information on how to turn this feature on in the browser settings should they wish to do so". Very few advertising companies actually supported DNT, due to a lack of regulatory or voluntary requirements for its use, and unclear standards over how websites should respond to
1254-449: The specification. Many user agents show different behavior in loading pages from the history store or cache depending on whether the protocol is HTTP or HTTPS. The Cache-Control: no-cache HTTP/1.1 header field is also intended for use in requests made by the client. It is a means for the browser to tell the server and any intermediate caches that it wants a fresh version of the resource. The Pragma: no-cache header field, defined in
1292-545: The use of Do Not Track actually be a choice until after the feature was implemented in Internet Explorer 10. According to Fielding, Microsoft knew its Do Not Track signals would be ignored, and that its goal was to effectively give an illusion of privacy while still catering to their own interests. On October 9, 2012, Fielding's patch was commented out , restoring the previous behavior. On April 3, 2015, Microsoft announced that starting with Windows 10 , it would comply with
1330-406: The user consents to be tracked (opt-in) , or null (no header sent) if the user has not expressed a preference. The default behavior required by the standard is not to send the header unless the user enables the setting via their browser or their choice is implied by the use of that specific browser. In 2007, several consumer advocacy groups asked the U.S. Federal Trade Commission (FTC) to create
1368-730: The user's wish to have their information not be sold or used by ad trackers. GPC was developed in 2020 by privacy technology researchers such as Wesleyan University professor Sebastian Zimmeck and former Chief Technologist of the Federal Trade Commission Ashkan Soltani , as well as a group of privacy-focused companies including the Electronic Frontier Foundation , Automattic (owner of Tumblr and WordPress ), and more. The signal has been implemented by DuckDuckGo 's private browser and extension, The New York Times , and privacy browser Brave and
1406-558: Was a member of the interim OpenSolaris Boards until he resigned from the community in 2008. He chaired the Apache Software Foundation for its first three years and sat on its board of directors until May 2014. Between 2001 and 2006, Fielding worked on Waka, an application protocol intended as "a binary, token-based replacement for HTTP ". It was "designed to match the efficiency of the REST architectural style". He coined
1444-550: Was deprecated in June 2012 because of the inconveniences it caused when non-standard fields became standard. An earlier restriction on use of Downgraded- was lifted in March 2013. A few fields can contain comments (i.e. in User-Agent, Server, Via fields), which can be ignored by software. Many field values may contain a quality ( q ) key-value pair separated by equals sign , specifying
#457542