In computing , Resource Directory Description Language ( RDDL ) is an extension of XHTML Basic 1.0. An RDDL document, called a Resource Directory, provides a package of information about some target. The targets which RDDL was designed to describe are XML namespaces . The specification for RDDL has no official standing and has not been considered nor approved by any organization (e.g., W3C).
65-428: RDDL is designed to allow both human readers and software robots to find any sort of resource associated with a particular namespace. Instead of putting one thing at the end of a namespace URI , RDDL puts a document there that lists all the machine-processable documents that might be available, including: An RDDL document identifies each related resource by a resource element in the http://www.rddl.org/ namespace, which
130-465: A namespace is an abstract domain to which a collection of element and attribute names can be assigned. The namespace name is a character string which must adhere to the generic URI syntax. However, the name is generally not considered to be a URI, because the URI specification bases the decision not only on lexical components, but also on their intended use. A namespace name does not necessarily imply any of
195-450: A serial number . Once assigned a number and published, an RFC is never rescinded or modified; if the document requires amendments, the authors publish a revised document. Therefore, some RFCs supersede others; the superseded RFCs are said to be deprecated , obsolete , or obsoleted by the superseding RFC. Together, the serialized RFCs compose a continuous historical record of the evolution of Internet standards and practices. The RFC process
260-483: A URL is simply a URI that happens to point to a resource over a network. However, in non-technical contexts and in software for the World Wide Web, the term "URL" remains widely used. Additionally, the term "web address" (which has no formal definition) often occurs in non-technical publications as a synonym for a URI that uses the http or https schemes. Such assumptions can lead to confusion, for example, in
325-539: A brief description of the purpose of the link. This programming-language -related article is a stub . You can help Misplaced Pages by expanding it . Uniform Resource Identifier A Uniform Resource Identifier ( URI ), formerly Universal Resource Identifier , is a unique sequence of characters that identifies an abstract or physical resource, such as resources on a webpage, mail address, phone number, books, real-world objects such as people and places, concepts. URIs are used to identify anything described using
390-526: A common set of terms such as "MUST" and "NOT RECOMMENDED" (as defined by RFC 2119 and 8174 ), augmented Backus–Naur form (ABNF) ( RFC 5234 ) as a meta-language, and simple text-based formatting, in order to keep the RFCs consistent and easy to understand. The RFC series contains three sub-series for IETF RFCs: BCP, FYI, and STD. Best Current Practice (BCP) is a sub-series of mandatory IETF RFCs not on standards track. For Your Information (FYI)
455-440: A computer filesystem or an Intranet ) are Uniform Resource Locators ( URLs ). Therefore, URLs are a subset of URIs, ie. every URL is a URI (and not necessarily the other way around). Other URIs provide only a unique name, without a means of locating or retrieving the resource or information about it; these are Uniform Resource Names (URNs). The web technologies that use URIs are not limited to web browsers . URIs and URLs have
520-557: A copy of that book. A Uniform Resource Locator (URL) is a URI that specifies the means of acting upon or obtaining the representation of a resource, i.e. specifying both its primary access mechanism and network location. For example, the URL http://example.org/wiki/Main_Page refers to a resource identified as /wiki/Main_Page , whose representation is obtainable via the Hypertext Transfer Protocol ( http: ) from
585-554: A distinction which has caused confusion as to how to distinguish the two. The TAG published an e-mail in 2005 with a solution of the problem, which became known as the httpRange-14 resolution . The W3C subsequently published an Interest Group Note titled Cool URIs for the Semantic Web , which explained the use of content negotiation and the HTTP 303 response code for redirections in more detail. A Uniform Resource Name (URN)
650-612: A need to distinguish a string that provided an address for a resource from a string that merely named a resource emerged. Although not yet formally defined, the term Uniform Resource Locator came to represent the former, and the more contentious Uniform Resource Name came to represent the latter. In July 1992 Berners-Lee's report on the Internet Engineering Task Force (IETF) "UDI (Universal Document Identifiers) BOF " mentions URLs (as Uniform Resource Locators), URNs (originally, as Unique Resource Numbers), and
715-482: A network host whose domain name is example.org . (In this case, HTTP usually implies it to be in the form of HTML and related code. In practice, that is not necessarily the case, as HTTP allows specifying arbitrary formats in its header.) A URN is analogous to a person's name, while a URL is analogous to their street address. In other words, a URN identifies an item and a URL provides a method for finding it. Technical publications, especially standards produced by
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#1732790089559780-573: A new submission which will receive a new serial number. Standards track documents are further divided into Proposed Standard and Internet Standard documents. Only the IETF, represented by the Internet Engineering Steering Group (IESG), can approve standards-track RFCs. If an RFC becomes an Internet Standard (STD), it is assigned an STD number but retains its RFC number. The definitive list of Internet Standards
845-577: A reminder that some URIs act as addresses by having schemes implying network accessibility, regardless of any such actual use. As URI-based standards such as Resource Description Framework make evident, resource identification need not suggest the retrieval of resource representations over the Internet, nor need they imply network-based resources at all. The Semantic Web uses the HTTP URI scheme to identify both documents and concepts for practical uses,
910-516: A scheme component followed by a colon ( : ). A path segment that contains a colon character (e.g., foo:bar ) cannot be used as the first path segment of a relative reference if its path component does not begin with a slash ( / ), as it would be mistaken for a scheme component. Such a path segment must be preceded by a dot path segment (e.g., ./foo:bar ). Web document markup languages frequently use URI references to point to other resources, such as external documents or specific portions of
975-466: A shared history. In 1990, Tim Berners-Lee's proposals for hypertext implicitly introduced the idea of a URL as a short string representing a resource that is the target of a hyperlink . At the time, people referred to it as a "hypertext name" or "document name". Over the next three and a half years, as the World Wide Web's core technologies of HTML , HTTP , and web browsers developed,
1040-587: A similar fashion; BCP n refers to a certain RFC or set of RFCs, but which RFC or RFCs may change over time). An informational RFC can be nearly anything from April 1 jokes to widely recognized essential RFCs like Domain Name System Structure and Delegation ( RFC 1591 ). Some informational RFCs formed the FYI sub-series. An experimental RFC can be an IETF document or an individual submission to
1105-463: Is undefined if it has an associated delimiter and the delimiter does not appear in the URI; the scheme and path components are always defined. A component is empty if it has no characters; the scheme component is always non-empty. The authority component consists of subcomponents : This is represented in a syntax diagram as: [REDACTED] The URI comprises: The scheme- or implementation-specific reserved character + may be used in
1170-616: Is a URI that identifies a resource by name in a particular namespace. A URN may be used to talk about a resource without implying its location or how to access it. For example, in the International Standard Book Number (ISBN) system, ISBN 0-486-27557-4 identifies a specific edition of the William Shakespeare play Romeo and Juliet . The URN for that edition would be urn:isbn:0-486-27557-4 . However, it gives no information as to where to find
1235-591: Is a sub-series of informational RFCs promoted by the IETF as specified in RFC ; 1150 (FYI 1). In 2011, RFC 6360 obsoleted FYI 1 and concluded this sub-series. Standard (STD) used to be the third and highest maturity level of the IETF standards track specified in RFC 2026 (BCP 9). In 2011 RFC 6410 (a new part of BCP 9) reduced the standards track to two maturity levels. There are five streams of RFCs: IETF , IRTF , IAB , independent submission , and Editorial . Only
1300-539: Is a technique by which a command is appended to a URL, usually at the end, after a "?" token . It is commonly used in WebDAV as a mechanism of adding functionality to HTTP . In a versioning system, for example, to add a "checkout" command to a URL, it is written as http://editing.com/resource/file.php?command=checkout . It has the advantage of both being easy for CGI parsers and also acts as an intermediary between HTTP and underlying resource, in this case. In XML ,
1365-408: Is another of the four first of what were ARPANET nodes and the source of early RFCs. The ARC became the first network information center ( InterNIC ), which was managed by Elizabeth J. Feinler to distribute the RFCs along with other network information. From 1969 until 1998, Jon Postel served as the RFC editor . On his death in 1998, his obituary was published as RFC 2468 . Following
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#17327900895591430-438: Is customarily mapped to the rddl prefix. This element is a simple XLink (that is, it has an xlink:type attribute with the value simple) and its xlink:href attribute points to the related resource. Furthermore, the xlink:role attribute identifies the nature of the related resource and the optional xlink:arcrole attribute identifies the purpose of the related resource. An optional xlink:title attribute can provide
1495-413: Is documented in RFC 2026 ( The Internet Standards Process, Revision 3 ). The RFC production process differs from the standardization process of formal standards organizations such as International Organization for Standardization (ISO). Internet technology experts may submit an Internet Draft without support from an external institution. Standards-track RFCs are published with approval from
1560-602: Is now typical of Internet Draft documents, the precursor step before being approved as an RFC. In December 1969, researchers began distributing new RFCs via the newly operational ARPANET. RFC 1 , titled "Host Software", was written by Steve Crocker of the University of California, Los Angeles (UCLA), and published on April 7, 1969. Although written by Steve Crocker, the RFC had emerged from an early working group discussion between Steve Crocker, Steve Carr, and Jeff Rulifson . In RFC 3 , which first defined
1625-502: Is obsoleted by various newer RFCs, but SMTP itself is still "current technology", so it is not in "Historic" status. However, since BGP version 4 has entirely superseded earlier BGP versions, the RFCs describing those earlier versions, such as RFC 1267 , have been designated historic. Status unknown is used for some very old RFCs, where it is unclear which status the document would get if it were published today. Some of these RFCs would not be published at all today; an early RFC
1690-562: Is submitted as plain ASCII text and is published in that form, but may also be available in other formats . For easy access to the metadata of an RFC, including abstract, keywords, author(s), publication date, errata, status, and especially later updates, the RFC Editor site offers a search form with many features. A redirection sets some efficient parameters, example: rfc:5000. The official International Standard Serial Number (ISSN) of
1755-492: Is the Official Internet Protocol Standards. Previously STD 1 used to maintain a snapshot of the list. When an Internet Standard is updated, its STD number stays the same, now referring to a new RFC or set of RFCs. A given Internet Standard, STD n , may be RFCs x and y at a given time, but later the same standard may be updated to be RFC z instead. For example, in 2007 RFC 3700
1820-692: The Internet Research Task Force (IRTF), and an independent stream from other outside sources. A new model was proposed in 2008, refined, and published in August 2009, splitting the task into several roles, including the RFC Series Advisory Group (RSAG). The model was updated in 2012. The streams were also refined in December 2009, with standards defined for their style. In January 2010, the RFC Editor function
1885-615: The Resource Description Framework (RDF), for example, concepts that are part of an ontology defined using the Web Ontology Language (OWL), and people who are described using the Friend of a Friend vocabulary would each have an individual URI. URIs which provide a means of locating and retrieving information resources on a network (either on the Internet or on another private network, such as
1950-561: The World Wide Web Consortium's (W3C) Technical Architecture Group (TAG) published a guide to best practices and canonical URIs for publishing multiple versions of a given resource. For example, content might differ by language or by size to adjust for capacity or settings of the device used to access that content. In August 2002, IETF RFC 3305 pointed out that the term "URL" had, despite widespread public use, faded into near obsolescence, and serves only as
2015-499: The IETF and by the W3C, normally reflect a view outlined in a W3C Recommendation of 30 July 2001, which acknowledges the precedence of the term URI rather than endorsing any formal subdivision into URL and URN. URL is a useful but informal concept: a URL is a type of URI that identifies a resource via a representation of its primary access mechanism (e.g., its network "location"), rather than by some other attributes it may have. As such,
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2080-627: The IETF creates BCPs and RFCs on the standards track. The IAB publishes informational documents relating to policy or architecture. The IRTF publishes the results of research, either as informational documents or as experiments. Independent submissions are published at the discretion of the Independent Submissions Editor. Non-IETF documents are reviewed by the IESG for conflicts with IETF work. IRTF and independent RFCs generally contain relevant information or experiments for
2145-568: The IETF, and are usually produced by experts participating in IETF Working Groups , which first publish an Internet Draft. This approach facilitates initial rounds of peer review before documents mature into RFCs. The RFC tradition of pragmatic, experience-driven, after-the-fact standards authorship accomplished by individuals or small working groups can have important advantages over the more formal, committee-driven process typical of ISO and national standards bodies. Most RFCs use
2210-555: The IETF. The new RFC changed the meaning of U in URI from "Universal" to "Uniform." In December 1999, RFC 2732 provided a minor update to RFC 2396, allowing URIs to accommodate IPv6 addresses. A number of shortcomings discovered in the two specifications led to a community effort, coordinated by RFC 2396 co-author Roy Fielding , that culminated in the publication of IETF RFC 3986 in January 2005. While obsoleting
2275-514: The Internet at large not in conflict with IETF work. compare RFC 4846 , 5742 and 5744 . The Editorial Stream is used to effect editorial policy changes across the RFC series (see RFC 9280 ). The official source for RFCs on the World Wide Web is the RFC Datatracker. Almost any published RFC can be retrieved via a URL of the form https://datatracker.ietf.org/doc/html/rfc5000, shown for RFC 5000 . Every RFC
2340-669: The Internet community, other documents also called requests for comments have been published, as in U.S. Federal government work, such as the National Highway Traffic Safety Administration . The inception of the RFC format occurred in 1969 as part of the seminal ARPANET project. Today, it is the official publication channel for the Internet Engineering Task Force (IETF), the Internet Architecture Board (IAB), and – to some extent –
2405-436: The RFC Editor. A draft is designated experimental if it is unclear the proposal will work as intended or unclear if the proposal will be widely adopted. An experimental RFC may be promoted to standards track if it becomes popular and works well. The Best Current Practice subseries collects administrative documents and other texts which are considered as official rules and not only informational , but which do not affect over
2470-826: The RFC Series Approval Board (RSAB). It also established a new Editorial Stream for the RFC Series and concluded the RSOC. The role of the RSE was changed to the RFC Series Consulting Editor (RSCE). In September 2022, Alexis Rossi was appointed to that position. Requests for Comments were originally produced in non- reflowable text format. In August 2019, the format was changed so that new documents can be viewed optimally in devices with varying display sizes. The RFC Editor assigns each RFC
2535-451: The RFC series is 2070-1721. Not all RFCs are standards. Each RFC is assigned a designation with regard to status within the Internet standardization process. This status is one of the following: Informational , Experimental , Best Current Practice , Standards Track , or Historic . Once submitted, accepted, and published, an RFC cannot be changed. Errata may be submitted, which are published separately. More significant changes require
2600-696: The RFC series, Crocker started attributing the RFC series to the Network Working Group. Rather than being a formal committee, it was a loose association of researchers interested in the ARPANET project. In effect, it included anyone who wanted to join the meetings and discussions about the project. Many of the subsequent RFCs of the 1970s also came from UCLA, because UCLA is one of the first of what were Interface Message Processors (IMPs) on ARPANET. The Augmentation Research Center (ARC) at Stanford Research Institute , directed by Douglas Engelbart ,
2665-807: The URI syntax is a federated and extensible naming system wherein each scheme's specification may further restrict the syntax and semantics of identifiers using that scheme. The URI generic syntax is a superset of the syntax of all URI schemes. It was first defined in RFC 2396 , published in August 1998, and finalized in RFC 3986 , published in January 2005. A URI is composed from an allowed set of ASCII characters consisting of reserved characters (gen-delims: : , / , ? , # , [ , ] , and @ ; sub-delims: ! , $ , & , ' , ( , ) , * , + , , , ; , and = ), unreserved characters ( uppercase and lowercase letters , decimal digits , - , . , _ , and ~ ), and
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2730-430: The allowed set or is being used as a delimiter of, or within, the component. A percent-encoding of an identifying data octet is a sequence of three characters, consisting of the character % followed by the two hexadecimal digits representing that octet's numeric value. The URI generic syntax consists of five components organized hierarchically in order of decreasing significance from left to right: A component
2795-454: The basis for namespace names in addition to URI references. RFC (identifier) A Request for Comments ( RFC ) is a publication in a series from the principal technical development and standards-setting bodies for the Internet , most prominently the Internet Engineering Task Force (IETF). An RFC is authored by individuals or groups of engineers and computer scientists in
2860-468: The case of XML namespaces that have a visual similarity to resolvable URIs . Specifications produced by the WHATWG prefer URL over URI , and so newer HTML5 APIs use URL over URI . Standardize on the term URL. URI and IRI [Internationalized Resource Identifier] are just confusing. In practice a single algorithm is used for both so keeping them distinct is not helping anyone. URL also easily wins
2925-407: The character % . Syntax components and subcomponents are separated by delimiters from the reserved characters (only from generic reserved characters for components) and define identifying data represented as unreserved characters, reserved characters that do not act as delimiters in the component and subcomponent respectively, and percent-encodings when the corresponding character is outside
2990-552: The existence of URLs and URNs. Most importantly, it defined a formal syntax for Universal Resource Identifiers (i.e. URL-like strings whose precise syntaxes and semantics depended on their schemes). In addition, the RFC 1630 attempted to summarize the syntaxes of URL schemes in use at the time. It acknowledged -- but did not standardize —the existence of relative URLs and fragment identifiers. In December 1994, RFC 1738 formally defined relative and absolute URLs, refined
3055-648: The expiration of the original ARPANET contract with the U.S. federal government, the Internet Society, acting on behalf of the IETF, contracted with the Networking Division of the University of Southern California (USC) Information Sciences Institute (ISI) to assume the editorship and publishing responsibilities under the direction of the IAB. Sandy Ginoza joined USC/ISI in 1999 to work on RFC editing, and Alice Hagens in 2005. Bob Braden took over
3120-460: The form of a memorandum describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems. It is submitted either for peer review or to convey new concepts, information, or, occasionally, engineering humor. The IETF adopts some of the proposals published as RFCs as Internet Standards . However, many RFCs are informational or experimental in nature and are not standards. The RFC system
3185-523: The general URL syntax, defined how to resolve relative URLs to absolute form, and better enumerated the URL schemes then in use. The agreed definition and syntax of URNs had to wait until the publication of IETF RFC 2141 in May 1997. The publication of IETF RFC 2396 in August 1998 saw the URI syntax become a separate specification and most of the parts of RFCs 1630 and 1738 relating to URIs and URLs in general were revised and expanded by
3250-490: The global community of computer network researchers in general. The authors of the first RFCs typewrote their work and circulated hard copies among the ARPA researchers. Unlike the modern RFCs, many of the early RFCs were actual Requests for Comments and were titled as such to avoid sounding too declarative and to encourage discussion. The RFC leaves questions open and is written in a less formal style. This less formal style
3315-407: The need to charter a new working group. In November 1992 the IETF "URI Working Group" met for the first time. During the debate over defining URLs and URNs, it became evident that the concepts embodied by the two terms were merely aspects of the fundamental, overarching, notion of resource identification . In June 1994, the IETF published Berners-Lee's first Request for Comments that acknowledged
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#17327900895593380-475: The path, query and fragment, and the generic reserved character ? may be used in the query and fragment. The following figure displays example URIs and their component parts. DOIs ( digital object identifiers ) fit within the Handle System and fit within the URI system, as facilitated by appropriate syntax . A URI reference is either a URI or a relative reference when it does not begin with
3445-417: The prior standard, it did not render the details of existing URL schemes obsolete; RFC 1738 continues to govern such schemes except where otherwise superseded. IETF RFC 2616 for example, refines the http scheme. Simultaneously, the IETF published the content of RFC 3986 as the full standard STD 66, reflecting the establishment of the URI generic syntax as an official Internet protocol. In 2001,
3510-689: The program were included the RFC Editor Model (Version 3) as defined in RFC 9280 , published in June 2022. Generally, the new model is intended to clarify responsibilities and processes for defining and implementing policies related to the RFC series and the RFC Editor function. Changes in the new model included establishing the position of the RFC Consulting Editor, the RFC Series Working Group (RSWG), and
3575-427: The recommendation to use source filtering to make DoS attacks more difficult ( RFC 2827 : " Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing ") is BCP 38 . A historic RFC is one that the technology defined by the RFC is no longer recommended for use, which differs from "Obsoletes" header in a replacement RFC. For example, RFC 821 ( SMTP ) itself
3640-429: The role of RFC project lead, while Joyce K. Reynolds continued to be part of the team until October 13, 2006. In July 2007, streams of RFCs were defined, so that the editing duties could be divided. IETF documents came from IETF working groups or submissions sponsored by an IETF area director from the Internet Engineering Steering Group . The IAB can publish its own documents. A research stream of documents comes from
3705-406: The same logical document: Resolving a URI reference against a base URI results in a target URI . This implies that the base URI exists and is an absolute URI (a URI with no fragment component). The base URI can be obtained, in order of precedence, from: Within a representation with a well defined base URI of a relative reference is resolved to its target URI as follows: URL munging
3770-425: The scheme, userinfo, host, path, query, and fragment, and the scheme- or implementation-specific reserved characters ! , $ , & , ' , ( , ) , * , , , ; , and = may be used in the userinfo, host, path, query, and fragment. Additionally, the generic reserved character : may be used in the userinfo, path, query and fragment, the generic reserved characters @ and / may be used in
3835-452: The search result popularity contest. While most URI schemes were originally designed to be used with a particular protocol , and often have the same name, they are semantically different from protocols. For example, the scheme http is generally used for interacting with web resources using HTTP, but the scheme file has no protocol. A URI has a scheme that refers to a specification for assigning identifiers within that scheme. As such,
3900-468: The semantics of URI schemes; for example, a namespace name beginning with http: may have no connotation to the use of the HTTP . Originally, the namespace name could match the syntax of any non-empty URI reference, but the use of relative URI references was deprecated by the W3C. A separate W3C specification for namespaces in XML 1.1 permits Internationalized Resource Identifier (IRI) references to serve as
3965-572: The wire data . The border between standards track and BCP is often unclear. If a document only affects the Internet Standards Process, like BCP 9, or IETF administration, it is clearly a BCP. If it only defines rules and regulations for Internet Assigned Numbers Authority (IANA) registries it is less clear; most of these documents are BCPs, but some are on the standards track. The BCP series also covers technical recommendations for how to practice Internet standards; for instance,
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#17327900895594030-400: Was an Internet Standard—STD 1—and in May 2008 it was replaced with RFC 5000 , so RFC 3700 changed to Historic , RFC 5000 became an Internet Standard, and as of May 2008 STD 1 is RFC 5000 . as of December 2013 RFC 5000 is replaced by RFC 7100 , updating RFC 2026 to no longer use STD 1. (Best Current Practices work in
4095-416: Was invented by Steve Crocker in 1969 to help record unofficial notes on the development of ARPANET . RFCs have since become official documents of Internet specifications , communications protocols , procedures, and events. According to Crocker, the documents "shape the Internet's inner workings and have played a significant role in its success," but are not widely known outside the community. Outside of
4160-493: Was moved to a contractor, Association Management Solutions, with Glenn Kowack serving as interim series editor. In late 2011, Heather Flanagan was hired as the permanent RFC Series Editor (RSE). Also at that time, an RFC Series Oversight Committee (RSOC) was created. In 2020, the IAB convened the RFC Editor Future Development program to discuss potential changes to the RFC Editor model. The results of
4225-458: Was often just that: a simple Request for Comments, not intended to specify a protocol, administrative procedure, or anything else for which the RFC series is used today. The general rule is that original authors (or their employers, if their employment conditions so stipulate) retain copyright unless they make an explicit transfer of their rights. An independent body, the IETF Trust, holds
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