Hypertext Transfer Protocol -- HTTP/1

1 Fielding, et alStandards Track[Page 1]Network Working Group R. FieldingRequest for Comments: 2616 UC IrvineObsoletes: 2068 J. GettysCategory: Standards Track Compaq/W3C J. C. Mogul Compaq H. Frystyk W3C/MIT L. Masinter Xerox P.

2 Leach Microsoft T. Berners-Lee W3C/MIT June, 1999 Hypertext Transfer Protocol -- of this MemoThis document specifies an Internet standards track Protocol for the Internet community, and requests discussion andsuggestions for improvements. Please refer to the current edition of the Internet Official Protocol Standards (STD1) for the standardization state and status of this Protocol . Distribution of this memo is NoticeCopyright (C) The Internet Society (1999). All Rights Hypertext Transfer Protocol ( http ) is an application-level Protocol for distributed, collaborative, hypermediainformation systems.

3 It is a generic, stateless, Protocol which can be used for many tasks beyond its use forhypertext, such as name servers and distributed object management systems, through extension of its requestmethods, error codes and headers [47]. A feature of http is the typing and negotiation of data representation,allowing systems to be built independently of the data being has been in use by the World-Wide Web global information initiative since 1990. This specification definesthe Protocol referred to as , and is an update to RFC 2068 [33].RFC 2616 , 1999 Fielding, et alStandards Track[Page 2]Table of ContentsHYPERTEXT Transfer Protocol -- of this Memo ..1 Copyright ..1 Table of .. Operation ..102 Notational Conventions and Generic Grammar .. BNF .. Rules ..123 Protocol Parameters .. Version .. Resource URL.

4 Comparison .. Formats .. Date .. Seconds .. Sets .. Charset .. Codings .. Codings .. Transfer Coding .. Types .. and Text Defaults .. Tokens .. Values .. Tags .. Units ..214 http Message .. Headers .. Length .. Header Fields ..23 RFC 2616 , 1999 Fielding, et alStandards Track[Page 3]5 Request .. Resource Identified by a Request .. Header Fields ..266 Response .. Code and Reason Phrase .. Header .. Header Fields .. Body .. Length ..298 Connections .. Connections .. Operation .. Servers .. Transmission Requirements .. Connections and Flow Control .. Connections for Error Status Messages .. of the 100 (Continue) Status .. Behavior if Server Prematurely Closes Connection ..339 Method Definitions .. and Idempotent Methods .. Methods .. Methods ..3710 Status Code Definitions.

5 1xx .. Switching Protocols .. 2xx .. OK .. Created .. Accepted .. Non-Authoritative Information .. No Reset Content .. Partial Content ..39 RFC 2616 , 1999 Fielding, et alStandards Track[Page 4] Multiple Moved Permanently .. Found .. See Other .. Not Modified .. Use (Unused) .. Temporary Redirect .. Error 4xx .. Bad Request .. Payment Required .. Not Found .. Method Not Allowed .. Not Acceptable .. Proxy Authentication Required .. Request Timeout .. Conflict .. Gone .. Length Required .. Precondition Request Entity Too Large .. Request-URI Too Long .. Unsupported Media Type .. Requested Range Not Expectation Failed .. Error 5xx .. Internal Server Error .. Not Implemented .. Bad Service Unavailable .. Gateway Timeout .. http Version Not Supported ..4511 Access Negotiation.

6 Negotiation ..4713 Caching in http .. Mechanisms .. User Agent Warnings .. to the Rules and Model .. Expiration .. Expiration .. Calculations .. 2616 , 1999 Fielding, et alStandards Track[Page 5] Expiration Values .. Multiple Model .. Dates .. Tag Cache Validators .. and Strong Validators .. for When to Use Entity Tags and Last-Modified Dates .. Conditionals .. Cacheability .. Responses From Caches .. and Hop-by-hop Headers .. Headers .. Headers .. Byte Ranges .. Negotiated Responses .. and Non-Shared Caches .. or Incomplete Response Cache Behavior .. Effects of GET and HEAD .. After Updates or Deletions .. Field Definitions .. is Cacheable .. May be Stored by Caches .. of the Basic Expiration Mechanism .. Revalidation and Reload Control Extensions .. Origin Server Operation.

7 80 RFC 2616 , 1999 Fielding, et alStandards Track[Page 6] .. Ranges .. Retrieval Requests ..9215 Security Considerations .. of Server Log Information .. of Sensitive Information .. Sensitive Information in URI s .. Issues Connected to Accept Headers .. Based On File and Path Headers and Issues .. Credentials and Idle and Caching .. of Service Attacks on .. Media Type message/ http and application/ http .. Media Type multipart/byteranges .. Applications .. Between http Entities and RFC 2045 to Canonical Form .. of Date Formats .. of Content-Encoding ..103 RFC 2616 , 1999 Fielding, et alStandards Track[Page 7] of Transfer -Encoding .. and Line Length Limitations .. with Previous Versions .. from .. with Persistent Connections .. from RFC Copyright ..10821 Index.

8 1091 PurposeThe Hypertext Transfer Protocol ( http ) is an application-level Protocol for distributed, collaborative, hypermediainformation systems. http has been in use by the World-Wide Web global information initiative since 1990. Thefirst version of http , referred to as , was a simple Protocol for raw data Transfer across the , as defined by RFC 1945 [6], improved the Protocol by allowing messages to be in the format of MIME-like messages, containing metainformation about the data transferred and modifiers on the request/responsesemantics. However, does not sufficiently take into consideration the effects of hierarchical proxies,caching, the need for persistent connections, or virtual hosts. In addition, the proliferation of incompletely-implemented applications calling themselves has necessitated a Protocol version change in order for twocommunicating applications to determine each other s true specification defines the Protocol referred to as.

9 This Protocol includes more stringentrequirements than in order to ensure reliable implementation of its information systems require more functionality than simple retrieval, including search, front-end update,and annotation. http allows an open-ended set of methods and headers that indicate the purpose of a request [47].It builds on the discipline of reference provided by the Uniform Resource Identifier (URI) [3], as a location (URL)[4] or name (URN) [20], for indicating the resource to which a method is to be applied. Messages are passed in aformat similar to that used by Internet mail [9] as defined by the Multipurpose Internet Mail Extensions (MIME) [7]. http is also used as a generic Protocol for communication between user agents and proxies/gateways to otherInternet systems, including those supported by the SMTP [16], NNTP [13], FTP [18], Gopher [2], and WAIS [10]protocols.

10 In this way, http allows basic hypermedia access to resources available from diverse RequirementsThe key words MUST , MUST NOT , REQUIRED , SHALL , SHALL NOT , SHOULD , SHOULDNOT , RECOMMENDED , MAY , and OPTIONAL in this document are to be interpreted as described inRFC 2119 [34].An implementation is not compliant if it fails to satisfy one or more of the MUST or REQUIRED level requirementsfor the protocols it implements. An implementation that satisfies all the MUST or REQUIRED level and all theSHOULD level requirements for its protocols is said to be unconditionally compliant ; one that satisfies all theMUST level requirements but not all the SHOULD level requirements for its protocols is said to be conditionallycompliant. RFC 2616 , 1999 Fielding, et alStandards Track[Page 8] TerminologyThis specification uses a number of terms to refer to the roles played by participants in, and objects of, the transport layer virtual circuit established between two programs for the purpose of basic unit of http communication, consisting of a structured sequence of octets matching the syntaxdefined in section 4 and transmitted via the http request message, as defined in section http response message, as defined in section network data object or service that can be identified by a URI, as defined in section Resources may beavailable in multiple representations ( multiple languages, data formats, size, and resolutions) or vary inother information transferred as the payload of a request or response.