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.The Hypertext Transfer Protocol (HTTP) is an Application Layer protocol for distributed, collaborative, hypermedia information systems.^ We're all familiar with HTTP (Hypertext Transfer Protocol).
  • HTTP 1.1 approved.(Hypertext Transfer Protocol)(Internet/Web/Online Service Information) | e-Business Advisor | Find Articles at BNET 28 January 2010 0:00 UTC findarticles.com [Source type: News]

 ^ Technical description of HTTP, or the hypertext transfer protocol .
  • Excite - Search: Hypertext Transfer Protocol 28 January 2010 0:00 UTC msxml.excite.com [Source type: FILTERED WITH BAYES]
  • Hypertext Transfer Protocol - Web - Copernic 28 January 2010 0:00 UTC ws.copernic.com [Source type: Academic]

 ^ HTTP stands for hypertext transfer protocol.
  • Protocols 28 January 2010 0:00 UTC www.cs.iupui.edu [Source type: FILTERED WITH BAYES]

 [1]
.HTTP is a request/response standard typical of client-server computing.^ In addition, there is no method of transmitting a request which is not a response from the HTTP server to the HTTP client.
  • COMMUNICATION METHOD AND APPARATUS USING HYPERTEXT TRANSFER PROTOCOL - Patent application 28 January 2010 0:00 UTC www.faqs.org [Source type: Reference]

 ^ A client is the computer requesting these services.
  • InfoChannel > Customer Care > FAQ's > Other FAQ's 28 January 2010 0:00 UTC www.infochan.com [Source type: General]

 ^ HTTP Responses from servers to clients.
  • Overview of Hypertext Transfer Protocol 28 January 2010 0:00 UTC www.cs.sfu.ca [Source type: FILTERED WITH BAYES]

 .In HTTP, web browsers or spiders typically act as clients, while an application running on the computer hosting the web site acts as a server.^ Each HTTP request from the Web browser or other Web client applications consists of three parts: .
  • Uploading Files with Beans - O'Reilly Media 28 January 2010 0:00 UTC onjava.com [Source type: Reference]

 ^ Typically, an HTTP client initiates a request.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ A browser is an HTTP client because it sends requests to an HTTP server (Web server), which then sends responses back to the client.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 .The client, which submits HTTP requests, is also referred to as the user agent.^ Typically, an HTTP client initiates a request.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Details user agent making the request .
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ HTTP Requests sent from clients to servers.
  • Overview of Hypertext Transfer Protocol 28 January 2010 0:00 UTC www.cs.sfu.ca [Source type: FILTERED WITH BAYES]

 .The responding server, which stores or creates resources such as HTML files and images, may be called the origin server.^ The server on which a given resource resides or is to be created.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ PUT Send a file to be stored on the server.

 ^ Images as part of HTML file (also may apply to audio and video) .
  • Initiatives: Web Content Guidance 28 January 2010 0:00 UTC www.archives.gov [Source type: Reference]

 .In between the user agent and origin server may be several intermediaries, such as proxies, gateways, and tunnels.^ The origin server will then send an HTTP Response to the user agent.
  • Hypertext Transfer Protocol - Hill2dot0 28 January 2010 0:00 UTC www.hill2dot0.com [Source type: Reference]

 ^ See also gateway and proxy server.
  • Glossary of Messaging Terms 28 January 2010 0:00 UTC www.as400-email.com [Source type: Reference]

 ^ The "*" value MUST NOT be generated by a proxy server; it may only be generated by an origin server.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
.HTTP is not constrained in principle to using TCP/IP, although this is its most popular implementation platform.^ HTTP is not constrained to using TCP/IP and its supporting layers, although this is its most popular application on the Internet.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ HTTP im TCP/IP‑Protokollstapel : .
  • Lexikon: Hypertext Transfer Protocol - ComputerBase 28 January 2010 0:00 UTC www.computerbase.de [Source type: General]

 ^ Note: that while the Windows 95 platform is no longer officially supported, the control will work provided that the OSR2 and TCP/IP stack updates have been installed.
  • Catalyst File Transfer provides a single interface for sending and receiving files 28 January 2010 0:00 UTC www.hallogram.com [Source type: Reference]

 .Indeed HTTP can be "implemented on top of any other protocol on the Internet, or on other networks."^ Indeed HTTP can be "implemented on top of any other protocol on the Internet, or on other networks.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ This does not preclude HTTP from being implemented on top of any other protocol on the Internet, or on other networks.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ The HTTPS protocol is in fact two protocols running on top of each other.
  • Hyper_Text_Transfer_Protocol - The Wireshark Wiki 28 January 2010 0:00 UTC wiki.wireshark.org [Source type: FILTERED WITH BAYES]

 .HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used.^ Http protocols provide this kind of security.
  • Hypertext Transfer Protocol Over Secure Socket Layer (HTTPS) Information | Business.com 28 January 2010 0:00 UTC www.business.com [Source type: General]
  • Hypertext Transfer Protocol Over Secure Socket Layer (HTTPS) – Web Listings 28 January 2010 0:00 UTC www.business.com [Source type: General]

 ^ HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used, and the mapping of the HTTP/1.1 request and response structures onto the transport data units of the protocol in question is outside the scope of this specification.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

 ^ HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used."
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 [2]
.Resources to be accessed by HTTP are identified using Uniform Resource Identifiers (URIs)—or, more specifically, Uniform Resource Locators (URLs)—using the http or https URI schemes.^ This section defines the scheme-specific syntax and semantics for http URLs.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Uniform Resource Locator (URL), which allows users to access documents in a standard way using the Hypertext Transfer Protocol (HTTP).
  • hypertext transfer | Tags | ComputerWeekly.com 28 January 2010 0:00 UTC www.computerweekly.com [Source type: News]

 ^ THTP uses HTTP's URI naming scheme.
  • draft-gershenfeld-thtp-00 - Trivial Hypertext Transfer Protocol (THTP) 28 January 2010 0:00 UTC tools.ietf.org [Source type: Academic]

Contents

History and standards development

.Its use for retrieving inter-linked resources, called hypertext documents, led to the establishment of the World Wide Web in 1990 by English physicist Tim Berners-Lee.^ Its use for retrieving inter-linked resources led to the establishment of the World Wide Web.
  • http://getglue.com/topics/p/hypertext_transfer_protocol 28 January 2010 0:00 UTC getglue.com [Source type: FILTERED WITH BAYES]

 ^ Hypertext resources are documents which provide links or connections to other documents.
  • LIS 2004 Lesson 1: Internet History & Protocols 28 January 2010 0:00 UTC www.valenciacc.edu [Source type: Reference]

 ^ HTTP has been in use by the World Wide Web ...
  • Excite - Search: Hypertext Transfer Protocol 28 January 2010 0:00 UTC msxml.excite.com [Source type: FILTERED WITH BAYES]
  • Hypertext Transfer Protocol - Web - Copernic 28 January 2010 0:00 UTC ws.copernic.com [Source type: Academic]
.The original version of HTTP, designated HTTP/1.0, was revised in HTTP/1.1. One of the characteristics in HTTP/1.0 was that it uses a separate connection to the same server for every document, while HTTP/1.1 can reuse the same connection to download, for instance, images for the just served page.^ When a browser accesses a page, the server uses HTTP to send the document to the user's computer.
  • SkyPoint Communications - Internet Service Provider - ISP - Minnesota 28 January 2010 0:00 UTC www.skypoint.com [Source type: Reference]

 ^ The current protocol uses a separate connection for the document and each inlined image.
  • HTTP-wg Archive: Minutes of Hypertext Transfer protocol BOF at 31st IETF 28 January 2010 0:00 UTC www.hpl.hp.com [Source type: FILTERED WITH BAYES]

 ^ HTTP will initiate a separate TCP connection for each file that needs to be downloaded.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 .Hence HTTP/1.1 may be faster as it takes time to set up such connections.^ Pogoplug The multimedia sharing device enhanced its capabilities, has faster performance and still ultra easy to set up.
  • Hypertext transfer protocol Definition from PC Magazine Encyclopedia 28 January 2010 0:00 UTC www.pcmag.com [Source type: General]

 ^ Because all HTTP transactions take place on an 8-bit clean connection, the default Content-Transfer-Encoding for all messages is binary.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]

 ^ In HTTP/1.1, a connection may be used for one or more request/response exchanges, although connections may be closed for a variety of reasons (see section 8.1 ).
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]
.The standards development of HTTP has been coordinated by the World Wide Web Consortium and the Internet Engineering Task Force (IETF), culminating in the publication of a series of Requests for Comments (RFCs), most notably RFC 2616 (June 1999), which defines HTTP/1.1, the version of HTTP in common use.^ When used in an HTTP request, its meaning is undefined.
  • The Hypertext Transfer Protocol (HTTP) Entity Tag ("ETag") Response Header in Write Operations 28 January 2010 0:00 UTC greenbytes.de [Source type: FILTERED WITH BAYES]
  • The Hypertext Transfer Protocol (HTTP) Entity Tag ("ETag") Response Header in Write Operations 28 January 2010 0:00 UTC www.greenbytes.de [Source type: Reference]

 ^ Internet Engineering Task Force ( IETF ) An industry standards body that governs and oversees Internet research and protocols.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 28 January 2010 0:00 UTC www.redhat.com [Source type: Reference]

 ^ HTTP has been in use by the World Wide Web ...
  • Excite - Search: Hypertext Transfer Protocol 28 January 2010 0:00 UTC msxml.excite.com [Source type: FILTERED WITH BAYES]
  • Hypertext Transfer Protocol - Web - Copernic 28 January 2010 0:00 UTC ws.copernic.com [Source type: Academic]
.Support for pre-standard HTTP/1.1 based on the then developing RFC 2068 was rapidly adopted by the major browser developers in early 1996. By March 1996, pre-standard HTTP/1.1 was supported in Netscape 2.0, Netscape Navigator Gold 2.01, Mosaic 2.7, Lynx 2.5, and in Internet Explorer 3.0. End user adoption of the new browsers was rapid.^ Popular browsers include Internet Explorer, Safari, and Netscape.
  • Glossary: A Teacher's Guide to School Web Sites 28 January 2010 0:00 UTC fcit.usf.edu [Source type: Reference]

 ^ Netscape Enterprise Server supports HTTP 1.1.
  • Netscape Enterprise Server Administrator's Guide: Appendix BHyperText Transfer Protocol 28 January 2010 0:00 UTC jgatech.com [Source type: Reference]

 ^ Netscape Navigator is also web browser application .
  • InfoChannel > Customer Care > FAQ's > Other FAQ's 28 January 2010 0:00 UTC www.infochan.com [Source type: General]

 .In March 1996, one web hosting company reported that over 40% of browsers in use on the Internet were HTTP 1.1 compliant.^ HTTP has been in use by the World Wide Web ...
  • Excite - Search: Hypertext Transfer Protocol 28 January 2010 0:00 UTC msxml.excite.com [Source type: FILTERED WITH BAYES]

 ^ Web and HTTP in contexts where HTTP is not used.
  • Cover Pages: W3C Forms New Web Services Resource Access (WS-RA) Working Group. 28 January 2010 0:00 UTC xml.coverpages.org [Source type: FILTERED WITH BAYES]

 ^ HTTP or hypertext transfer protocol, is the protocol used by the Internet for Web pages.
  • WebDev :: Web Developer Resources - Hypertext Transfer Protocol (HTTP) :: University of Memphis 28 January 2010 0:00 UTC www.memphis.edu [Source type: FILTERED WITH BAYES]

 .That same web hosting company reported that by June 1996, 65% of all browsers accessing their servers were HTTP/1.1 compliant.^ For example, there are many companies that host Web servers.
  • Protocol: FTP - Data ( File Transfer Protocol - Data Protocol ) 28 January 2010 0:00 UTC www.protocolbase.net [Source type: Reference]

 ^ The iPlanet Web Server 4.x supports HTTP 1.1.
  • Hypertext Transfer Protocol 28 January 2010 0:00 UTC www.wiu.edu [Source type: Reference]
  • "Administrator's Guide": HyperText Transfer Protocol 28 January 2010 0:00 UTC gosrch.grolier.com [Source type: Reference]

 ^ What is the difference between a web browser and a web server?
  • WWW FAQs: What is a UseNet newsgroup? 28 January 2010 0:00 UTC www.boutell.com [Source type: General]

 [3] The HTTP/1.1 standard as defined in RFC 2068 was officially released in January 1997. Improvements and updates to the HTTP/1.1 standard were released under RFC 2616 in June 1999.

HTTP session

.An HTTP session is a sequence of network request-response transactions.^ HTTP is based on a request/response model.
  • Hypertext Transfer Protocol 28 January 2010 0:00 UTC www.wiu.edu [Source type: Reference]
  • "Administrator's Guide": HyperText Transfer Protocol 28 January 2010 0:00 UTC gosrch.grolier.com [Source type: Reference]
  • "Netscape Enterprise Server Administrator's Guide": HyperText Transfer Protocol 28 January 2010 0:00 UTC docs.sun.com [Source type: Reference]

 ^ HTTP requests and responses can be pipelined on a connection.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ HTTP is an application layer protocol that is built on top of TCP/IP. The protocol sends requests and responses in ASCII characters that can easily be read.

 .An HTTP client initiates a request.^ Typically, an HTTP client initiates a request.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ The client which initiates a request.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ HTTP in its 1.0 version was “stateless”: each new request from a client established a new connection instead of handling all similar requests through the same connection between a specific client and server.
  • HTTP (computer science) -- Britannica Online Encyclopedia 28 January 2010 0:00 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

 .It establishes a Transmission Control Protocol (TCP) connection to a particular port on a host (typically port 80; see List of TCP and UDP port numbers).^ TCP port 80.
  • GIAC GCIH Practical - TCP Port 80 HTTP Header Exploitation 28 January 2010 0:00 UTC www.cgisecurity.com [Source type: Reference]

 ^ The layer is implemented by two protocols: the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

 ^ Notice the steps that two hosts preform to establish a TCP connection.
  • GIAC GCIH Practical - TCP Port 80 HTTP Header Exploitation 28 January 2010 0:00 UTC www.cgisecurity.com [Source type: Reference]

 .An HTTP server listening on that port waits for a client's request message.^ An HTTP server listening on that port waits for the client to send a request message.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ HTTP Message 4.1 Message Types HTTP messages consist of requests from client to server and responses from server to client.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Response After receiving and interpreting a request message, a server responds with an HTTP response message.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .Upon receiving the request, the server sends back a status line, such as "HTTP/1.1 200 OK", and a message of its own, the body of which is perhaps the requested resource, an error message, or some other information.^ An HTTP server listening on that port waits for the client to send a request message.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Send a GET request to the server for the desired file.

 ^ OK; no response--request received but no information exists to send back.
  • Protocol: HTTP ( HyperText Transfer Protocol ) 28 January 2010 0:00 UTC www.protocolbase.net [Source type: Reference]

Request message

The request message consists of the following:
  • Request line, such as GET /images/logo.gif HTTP/1.1, which requests a resource called /images/logo.gif from server
  • Headers, such as Accept-Language: en
  • An empty line
  • An optional message body
.The request line and headers must all end with <CR><LF> (that is, a carriage return followed by a line feed).^ However, the Expect request-header itself is end-to-end; it MUST be forwarded if the request is forwarded.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ A blank line: Each line ends with the carriage return and line feed ASCII characters.
  • Hypertext Transfer Protocol - Hill2dot0 28 January 2010 0:00 UTC www.hill2dot0.com [Source type: Reference]

 ^ The format for Request and Response messages is as follows: First line which ends with a Carriage Return (CR - ASCII 13) and a Line Feed (LF - ASCII 10).
  • Hypertext Transfer Protocol, HTTP, http header 28 January 2010 0:00 UTC www.rhyshaden.com [Source type: FILTERED WITH BAYES]

 .The empty line must consist of only <CR><LF> and no other whitespace.^ The empty line must consist of only and no other whitespace .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ If, on the other hand, the request appears (at least initially) to be acceptable and the client has indicated HTTP/1.1 compliance, the server must transmit an interim 100 response message after receiving the empty line terminating the request headers and continue processing the request.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

 ^ No CR or LF is allowed except in the final CRLF sequence.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .In the HTTP/1.1 protocol, all headers except Host are optional.^ Host request-headers are required in HTTP/1.1 requests.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ In the HTTP/1.1 protocol, all headers except Host are optional.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Content-Length Header in HTTP protocol .
  • Hypertext Transfer Protocol (HTTP) | Experts Exchange 28 January 2010 0:00 UTC www.experts-exchange.com [Source type: General]
.A request line containing only the path name is accepted by servers to maintain compatibility with HTTP clients before the HTTP/1.0 specification in RFC1945.^ HTTP Responses from servers to clients.
  • Overview of Hypertext Transfer Protocol 28 January 2010 0:00 UTC www.cs.sfu.ca [Source type: FILTERED WITH BAYES]

 ^ HTTP Message 4.1 Message Types HTTP messages consist of requests from client to server and responses from server to client.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Clients aren't required to use them, but HTTP 1.1 servers are required to honor requests that do use them.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 [4]

Request methods

.
An HTTP request made using telnet.^ When used in an HTTP request, its meaning is undefined.
  • The Hypertext Transfer Protocol (HTTP) Entity Tag ("ETag") Response Header in Write Operations 28 January 2010 0:00 UTC greenbytes.de [Source type: FILTERED WITH BAYES]
  • The Hypertext Transfer Protocol (HTTP) Entity Tag ("ETag") Response Header in Write Operations 28 January 2010 0:00 UTC www.greenbytes.de [Source type: Reference]

 ^ After a connection has been established, an HTTP GET request is made.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ The client can specify these three kinds of action using Cache- Control request directives: End-to-end reload The request includes a "no-cache" Cache-Control directive or, for compatibility with HTTP/1.0 clients, "Pragma: no-cache".
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 The request, response headers and response body are highlighted.
.HTTP defines eight methods (sometimes referred to as "verbs") indicating the desired action to be performed on the identified resource.^ The Method token indicates the method to be performed on the resource identified by the Request-URI .
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

 ^ HTTP defines eight methods (sometimes referred to as "verbs") indicating the desired action to be performed on the identified resource .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Internet protocols such as SMTP, NNTP, FTP, Gopher, and WAIS. For reference, HTTP uses the Uniform Resource Identifier (URI) ( RFC 1630 ), the Uniform Resource Location (URL) , and Uniform Resource Name (URN) (see RFC 2396 which supercedes RFC 1738 and RFC 1808 ), for indicating the resource on which a Method is to be applied (see later).
  • Hypertext Transfer Protocol, HTTP, http header 28 January 2010 0:00 UTC www.rhyshaden.com [Source type: FILTERED WITH BAYES]

 .What this resource represents, whether pre-existing data or data that is generated dynamically, depends on the implementation of the server.^ But in general, HTTP server implementers have a lot of freedom in how resources are implemented.
  • The Hypertext Transfer Protocol (HTTP) Entity Tag ("ETag") Response Header in Write Operations 28 January 2010 0:00 UTC greenbytes.de [Source type: FILTERED WITH BAYES]
  • The Hypertext Transfer Protocol (HTTP) Entity Tag ("ETag") Response Header in Write Operations 28 January 2010 0:00 UTC www.greenbytes.de [Source type: Reference]

 ^ The POST method requests that the destination server process the data within the request as a subordinate of the the Request-URI resource.
  • draft-gershenfeld-thtp-00 - Trivial Hypertext Transfer Protocol (THTP) 28 January 2010 0:00 UTC tools.ietf.org [Source type: Academic]

 ^ Servers MUST NOT depend on clients being able to choose deterministically between responses generated during the same second, if their expiration times overlap.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .Often, the resource corresponds to a file or the output of an executable residing on the server.^ The server on which a given resource resides or is to be created.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Accessible resources can be URL’s, files, directories, servlets, databases, execution paths, etc.
  • Glossary - Web Application Security Consortium 28 January 2010 0:00 UTC www.webappsec.org [Source type: Reference]

 ^ Common Gateway Interface : (Acronym - CGI) Programming standard for software to interface and execute applications residing on web servers.
  • Glossary - Web Application Security Consortium 28 January 2010 0:00 UTC www.webappsec.org [Source type: Reference]
HEAD
Asks for the response identical to the one that would correspond to a GET request, but without the response body. This is useful for retrieving meta-information written in response headers, without having to transport the entire content.
GET
Requests a representation of the specified resource. Note that GET should not be used for operations that cause side-effects, such as using it for taking actions in web applications. .One reason for this is that GET may be used arbitrarily by robots or crawlers, which should not need to consider the side effects that a request should cause.^ If it receives this directive, a cache SHOULD either respond using a cached entry that is consistent with the other constraints of the request, or respond with a 504 (Gateway Timeout) status.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Accept-Encoding = "Accept-Encoding" ":" #( encoding-mechanism ) An example of its use is Accept-Encoding: compress, gzip If no Accept-Encoding field is present in a request, the server should assume that the client will accept any encoding-mechanism .
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]

 ^ Unless it was a HEAD request, the response should include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose the one most appropriate.
  • WebDev :: Web Developer Resources - Hypertext Transfer Protocol (HTTP) :: University of Memphis 28 January 2010 0:00 UTC www.memphis.edu [Source type: FILTERED WITH BAYES]

 .See safe methods below.^ See safe methods below.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]
POST
Submits data to be processed (e.g., from an .HTML form) to the identified resource.^ HTML form ) to the identified resource.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ The most common form of Request-URI is that used to identify a resource on an origin server or gateway.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ An example Request-Line would be: GET http://www.w3.org/pub/WWW/TheProject.html HTTP/1.1 The most common form of Request-URI is that used to identify a resource on an origin server or gateway.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

 .The data is included in the body of the request.^ The data is included in the body of the request.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ For response messages, whether or not a message-body is included with a message is dependent on both the request method and the response status code ( section 6.1.1 ).
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Entity-Body = *OCTET An entity-body is included with a request message only when the request method calls for one.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]

 .This may result in the creation of a new resource or the updates of existing resources or both.^ This may result in the creation of a new resource or the updates of existing resources or both.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ The request has been fulfilled and resulted in a new resource being created.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

 ^ Created The request has been fulfilled and resulted in a new resource being created.
  • WebDev :: Web Developer Resources - Hypertext Transfer Protocol (HTTP) :: University of Memphis 28 January 2010 0:00 UTC www.memphis.edu [Source type: FILTERED WITH BAYES]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]
PUT
Uploads a representation of the specified resource.
DELETE
Deletes the specified resource.
TRACE
Echoes back the received request, so that a client can see what intermediate servers are adding or changing in the request.
OPTIONS
Returns the HTTP methods that the server supports for specified URL. .This can be used to check the functionality of a web server by requesting '*' instead of a specific resource.^ The server has fulfilled the partial GET request for the resource.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

 ^ This can be used to check the functionality of a web server by requesting '*' instead of a specific resource.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ The web browser will read the URI scheme ( https:// ), initiate the security protocol to the server, and once this secure connection is established, issue a HTTP request over it with the URI specified in the request.
  • Hyper_Text_Transfer_Protocol - The Wireshark Wiki 28 January 2010 0:00 UTC wiki.wireshark.org [Source type: FILTERED WITH BAYES]
CONNECT
Converts the request connection to a transparent .TCP/IP tunnel, usually to facilitate SSL-encrypted communication (HTTPS) through an unencrypted HTTP proxy.^ HTTP im TCP/IP‑Protokollstapel : .
  • Lexikon: Hypertext Transfer Protocol - ComputerBase 28 January 2010 0:00 UTC www.computerbase.de [Source type: General]

 ^ CONNECT Converts the request connection to a transparent TCP/IP tunnel , usually to facilitate SSL -encrypted communication (HTTPS) through an unencrypted HTTP proxy .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ HTTP communication usually takes place over TCP/IP connections.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 [5]
.HTTP servers are required to implement at least the GET and HEAD methods[6] and, whenever possible, also the OPTIONS method.^ HTTP servers are required to implement at least the GET and HEAD methods and, whenever possible, also the OPTIONS method.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ OPTIONS Returns the HTTP methods that the server supports for specified URL .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ To comply with HTTP 1.1, a server must support at least the GET and HEAD methods.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 [citation needed]

Safe methods

.Some methods (for example, HEAD, GET, OPTIONS and TRACE) are defined as safe, which means they are intended only for information retrieval and should not change the state of the server.^ Also, the methods OPTIONS and TRACE SHOULD NOT have side effects, and so are inherently idempotent.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ Methods GET, HEAD, OPTIONS and TRACE, being prescribed as safe, should be idempotent.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ HEAD, GET, OPTIONS, and TRACE) are defined as safe , which means they are intended only for information retrieval and should not change the state of the server (in other words, they should not have side effects ).
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 .In other words, they should not have side effects, beyond relatively harmless effects such as logging, caching, the serving of banner advertisements or incrementing a web counter.^ They MAY still have side effects, but a cache is not required to consider such side effects in its caching decisions.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ They may still have side effects, but a cache is not required to consider such side effects in its caching decisions.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ In other words, a cache can return a fresh .
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .Making arbitrary GET requests without regard to the context of the application's state should therefore be considered safe.^ These methods should be considered "safe."
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Among other tasks, the Transmission Control Protocol makes sure two processes (the client and server portions of an application, for example) can exchange data without errors.
  • Internet tools 101: the building blocks | RELease 1.0 | Find Articles at BNET 28 January 2010 0:00 UTC findarticles.com [Source type: News]

 ^ Session layer protocols are commonly found in applications that are considered stateful, that is, transactions are performed in a nonatomic manner and in a particular sequence or order.
  • Chapter 1: Introduction to Cisco Wide Area Application Services (WAAS) - Network World 28 January 2010 0:00 UTC www.networkworld.com [Source type: Reference]
.By contrast, methods such as POST, PUT and DELETE are intended for actions which may cause side effects either on the server, or external side effects such as financial transactions or transmission of email.^ Post Office Protocol: a method of retrieving email from a server.
  • AmeriTechnology Group : IT Outsourced Support - Managed Services - Computer Forensics 28 January 2010 0:00 UTC ameritechnologygroup.com [Source type: Reference]

 ^ This is because repeated requests can cause side effects, such as unwanted duplication of a transaction.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ GET —Requests the specified document HEAD —Requests only the header information for the document POST —Requests that the server accept some data from the client, such as form input for a CGI program PUT —Replaces the contents of a server’s document with data from the client .
  • Hypertext Transfer Protocol 28 January 2010 0:00 UTC www.wiu.edu [Source type: Reference]

 .Such methods are therefore not usually used by conforming web robots or web crawlers, which tend to make requests without regard to context or consequences.^ If-Match The If-Match request-header field is used with a method to make it conditional.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ Web and HTTP in contexts where HTTP is not used.
  • Cover Pages: W3C Forms New Web Services Resource Access (WS-RA) Working Group. 28 January 2010 0:00 UTC xml.coverpages.org [Source type: FILTERED WITH BAYES]

 ^ This accomplished using the GET request method.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]
.Despite the prescribed safety of GET requests, in practice their handling by the server is not technically limited in any way, and careless or deliberate programming can just as easily (or more easily, due to lack of user agent precautions) cause non-trivial changes on the server.^ If the client is a user agent, it should not change its document view from that which caused the request to be sent.
  • WebDev :: Web Developer Resources - Hypertext Transfer Protocol (HTTP) :: University of Memphis 28 January 2010 0:00 UTC www.memphis.edu [Source type: FILTERED WITH BAYES]

 ^ Details user agent making the request .
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ A client is the requesting program or user in a client/server relationship.
  • Glossary of Messaging Terms 28 January 2010 0:00 UTC www.as400-email.com [Source type: Reference]

 .This is discouraged, because it can cause problems for Web caching, search engines and other automated agents, which can make unintended changes on the server.^ This is discouraged, because it can cause problems for Web caching , search engines and other automated agents, which can make unintended changes on the server.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Despite the prescribed safety of GET requests, in practice their handling by the server is not technically limited in any way, and careless or deliberate programming can just as easily (or more easily, due to lack of user agent precautions) cause non-trivial changes on the server.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ A search engine allows you to find World Wide Web pages that contain specific words or phrases.
  • Internet Glossary 28 January 2010 0:00 UTC wings.avkids.com [Source type: General]

Idempotent methods and web applications

.Methods PUT and DELETE are defined to be idempotent, meaning that multiple identical requests should have the same effect as a single request.^ Idempotent Methods Methods may also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N > 0 identical requests is the same as for a single request.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Also, the methods OPTIONS and TRACE SHOULD NOT have side effects, and so are inherently idempotent.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ Idempotent Methods Methods can also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N > 0 identical requests is the same as for a single request.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 .Methods GET, HEAD, OPTIONS and TRACE, being prescribed as safe, should also be idempotent, as HTTP is a stateless protocol.^ These methods should be considered "safe."
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ HTTP is a stateless protocol.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Also, the methods OPTIONS and TRACE SHOULD NOT have side effects, and so are inherently idempotent.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
.By contrast, the POST method is not necessarily idempotent, and therefore sending an identical POST request multiple times may further affect state or cause further side effects (such as financial transactions).^ Also, the methods OPTIONS and TRACE SHOULD NOT have side effects, and so are inherently idempotent.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ Idempotent Methods Methods may also have the property of "idempotence" in that (aside from error or expiration issues) the side-effects of N > 0 identical requests is the same as for a single request.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ This is because repeated requests can cause side effects, such as unwanted duplication of a transaction.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 .In some cases this may be desirable, but in other cases this could be due to an accident, such as when a user does not realize that their action will result in sending another request, or they did not receive adequate feedback that their first request was successful.^ In some cases, this may even be preferable to sending a 406 response.
  • WebDev :: Web Developer Resources - Hypertext Transfer Protocol (HTTP) :: University of Memphis 28 January 2010 0:00 UTC www.memphis.edu [Source type: FILTERED WITH BAYES]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ You almost always want to use this, rather than headers-assq because Web browsers may send headers with arbitrary casing.
  • 4 HTTP: Hypertext Transfer Protocol 28 January 2010 0:00 UTC docs.plt-scheme.org [Source type: Reference]

 ^ Custom status codes can be used since, if the user agent encounters a code it does not recognize, it can use the first digit of the code to determine the general class of the response.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 .While web browsers may show alert dialog boxes to warn users in some cases where reloading a page may re-submit a POST request, it is generally up to the web application to handle cases where a POST request should not be submitted more than once.^ Simulation web form POST requests.
  • HTTP Controls, HTTP Components - for .Net ASP.Net Java ActiveX Delphi C/C++ 28 January 2010 0:00 UTC www.devdirect.com [Source type: Reference]

 ^ (A Web page often consists of more than one file.
  • Protocol: HTTP ( HyperText Transfer Protocol ) 28 January 2010 0:00 UTC www.protocolbase.net [Source type: Reference]

 ^ Users access the Web through a client application called a browser.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]
.Note that whether a method is idempotent is not enforced by the protocol or web server.^ Idempotent methods and web applications .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ However, note that idempotence is not enforced by the protocol or web server.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ The protocol most often used to transfer information from World Wide Web servers to browsers, which is why Web addresses begin with http://.
  • Dictionary - Others - Hypertext Transfer Protocol 28 January 2010 0:00 UTC www.computeruser.com [Source type: General]

 .It is perfectly possible to write a web application in which (for example) a database insert or other non-idempotent action is triggered by a GET or other request.^ It is perfectly possible to write a web application in which (for example) a database insert or update is triggered by a GET request - this would be a very normal example of what the spec refers to as "a change in server state."
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Idempotent methods and web applications .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Clients SHOULD NOT pipeline requests using non-idempotent methods or non-idempotent sequences of methods (see section 9.1.2).
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 .Ignoring this recommendation, however, may result in undesirable consequences if a user agent assumes that repeating the same request is safe when it isn't.^ Details user agent making the request .
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ Unexpected 1xx status responses MAY be ignored by a user agent.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ Page 46 9.1.2); other methods MUST NOT be automatically retried, although user agents MAY offer a human operator the choice of retrying the request.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

Status codes

See also: List of HTTP status codes
.In HTTP/1.0 and since, the first line of the HTTP response is called the status line and includes a numeric status code (such as "404") and a textual reason phrase (such as "Not Found").^ The Reason-Phrase is intended to give a short textual description of the Status-Code.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ In HTTP/1.0 and since, the first line of the HTTP response is called the status line and includes a numeric status code (such as "[ 404|404 ]") and a textual reason phrase (such as "Not Found").
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ See HTTP 1.0 Response Status Codes earlier.
  • Hypertext Transfer Protocol, HTTP, http header 28 January 2010 0:00 UTC www.rhyshaden.com [Source type: FILTERED WITH BAYES]

 .The way the user agent handles the response primarily depends on the code and secondarily on the response headers.^ The way the user agent handles the response primarily depends on the code and secondarily on the response headers.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Custom status codes can be used since, if the user agent encounters a code it does not recognize, it can use the first digit of the code to determine the general class of the response.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Despite the prescribed safety of GET requests, in practice their handling by the server is not technically limited in any way, and careless or deliberate programming can just as easily (or more easily, due to lack of user agent precautions) cause non-trivial changes on the server.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 .Custom status codes can be used since, if the user agent encounters a code it does not recognize, it can use the first digit of the code to determine the general class of the response.^ If this is the first license element used, then the user agent must : .
  • Widget Packaging and Configuration 28 January 2010 0:00 UTC dev.w3.org [Source type: Reference]

 ^ If this is the first description element encountered by the user agent, then the user agent must : .
  • Widget Packaging and Configuration 28 January 2010 0:00 UTC dev.w3.org [Source type: Reference]

 ^ A name element: If this is not the first name element encountered by the user agent, then the user agent must ignore this element .
  • Widget Packaging and Configuration 28 January 2010 0:00 UTC dev.w3.org [Source type: Reference]

 [7]
.Also, the standard reason phrases are only recommendations and can be replaced with "local equivalents" at the web developer's discretion.^ The reason phrases listed here are only recommendations -- they MAY be replaced by local equivalents without affecting the protocol.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ The reason phrases listed here are only recommended -- they may be replaced by local equivalents without affecting the protocol.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Also, the standard reason phrases are only recommendations and can be replaced with "local equivalents" at the web developer 's discretion.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 .If the status code indicated a problem, the user agent might display the reason phrase to the user to provide further information about the nature of the problem.^ The Status-Code is intended for use by automata and the Reason-Phrase is intended for the human user.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ DIGIT Reason-Phrase = * HTTP status codes are extensible.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ They also reveal information about the user.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 .The standard also allows the user agent to attempt to interpret the reason phrase, though this might be unwise since the standard explicitly specifies that status codes are machine-readable and reason phrases are human-readable.^ The Status-Code is intended for use by automata and the Reason-Phrase is intended for the human user.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ DIGIT Reason-Phrase = * HTTP status codes are extensible.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ If the status code indicated a problem, the user agent might display the reason phrase to the user to provide further information about the nature of the problem.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

Persistent connections

Main article: HTTP persistent connection
.In HTTP/0.9 and 1.0, the connection is closed after a single request/response pair.^ To comply with HTTP 1.1, clients must include the Host: header with each request accept responses with chunked data either support persistent connections , or include the " Connection: close " header with each request handle the " 100 Continue " response Return to Table of Contents Host: Header .
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 ^ The mapping of the HTTP/1.0 request and response structures onto the transport data units of the protocol in question is outside the scope of this specification.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]

 ^ Pipelining allows a client to send multiple HTTP GET requests over the same TCP connection without needing to wait for individual responses after each.
  • InformIT: Understanding Application Layer Protocols > HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.informit.com [Source type: FILTERED WITH BAYES]

 .In HTTP/1.1 a keep-alive-mechanism was introduced, where a connection could be reused for more than one request.^ In HTTP/1.1 a keep-alive-mechanism was introduced, where a connection could be reused for more than one request.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ HTTP is original stateless, which means, that the tcp connection is closed after each transmission.* * States are introduced for HTTP 1.1.
  • Vision and Reality of Hypertext and GUIs: 2.1.14 World Wide Web - mprove.de 28 January 2010 0:00 UTC www.mprove.de [Source type: FILTERED WITH BAYES]

 ^ Older HTTP/1.0 clients assumed a one-to-one relationship of IP addresses and servers; there was no other established mechanism for distinguishing the intended server of a request than the IP address to which that request was directed.
  • RFC2616 - Hypertext Transfer Protocol -- HTTP/1.1(8)_�й�Э�������� 28 January 2010 0:00 UTC www.cnpaf.net [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]
.Such persistent connections reduce lag perceptibly, because the client does not need to re-negotiate the TCP connection after the first request has been sent.^ Such persistent connections reduce lag perceptibly, because the client does not need to re-negotiate the TCP connection after the first request has been sent.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Messages are sent in succession over a persistent TCP connection.
  • Peer Distributed Transfer Protocol Specification 28 January 2010 0:00 UTC distribustream.org [Source type: Reference]

 ^ If a client does such a retry, it MUST NOT pipeline before it knows the connection is persistent.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]
.Version 1.1 of the protocol made bandwidth optimization improvements to HTTP/1.0. For example, HTTP/1.1 introduced chunked transfer encoding to allow content on persistent connections to be streamed, rather than buffered.^ For example, HTTP/1.1 introduced chunked transfer encoding to allow content on persistent connections to be streamed, rather than buffered.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ After a connection has been established, an HTTP GET request is made.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ An example is: Transfer-Encoding: chunked Fielding, et al.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 .HTTP pipelining further reduces lag time, allowing clients to send multiple requests before a previous response has been received to the first one.^ Pipelining allows a client to send multiple HTTP GET requests over the same TCP connection without needing to wait for individual responses after each.
  • InformIT: Understanding Application Layer Protocols > HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.informit.com [Source type: FILTERED WITH BAYES]

 ^ Pipelining A client that supports persistent connections MAY "pipeline" its requests (i.e., send multiple requests without waiting for each response).
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ A client that sends an HTTP/1.1 request MUST send a Host header.
  • RFC2616 - Hypertext Transfer Protocol -- HTTP/1.1(8)_�й�Э�������� 28 January 2010 0:00 UTC www.cnpaf.net [Source type: Reference]
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 .Another improvement to the protocol was byte serving, which is when a server transmits just the portion of a resource explicitly requested by a client.^ The HTTP client 1010 transmits the HTTP request message to the HTTP server 1000.
  • COMMUNICATION METHOD AND APPARATUS USING HYPERTEXT TRANSFER PROTOCOL - Patent application 28 January 2010 0:00 UTC www.faqs.org [Source type: Reference]

 ^ It forwards Requests to servers on behalf of clients.
  • Hypertext Transfer Protocol, HTTP, http header 28 January 2010 0:00 UTC www.rhyshaden.com [Source type: FILTERED WITH BAYES]

 ^ The server has fulfilled the partial GET request for the resource.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

HTTP session state

.HTTP is a stateless protocol.^ HTTP is a "stateless" protocol, meaning each command is executed independently, without any knowledge of the commands that came before it.
  • 2-2 Protocols and Standards | StudyNotes.net 28 January 2010 0:00 UTC studynotes.net [Source type: Reference]

 ^ After delivering the response, the server closes the connection (making HTTP a stateless protocol, i.e.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 ^ HTTP is a data transport protocol, version 1.0 was stateless meaning it did not maintain a any type of logical continuity from one request to the next.
  • GIAC GCIH Practical - TCP Port 80 HTTP Header Exploitation 28 January 2010 0:00 UTC www.cgisecurity.com [Source type: Reference]

 .The advantage of a stateless protocol is that hosts do not need to retain information about users between requests.^ They also reveal information about the user.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 ^ The advantage of a stateless protocol is that hosts do not need to retain information about users between requests, but this forces web developers to use alternative methods for maintaining users' states.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ It is strongly recommended that proxies used as a portal through a network firewall do not , by default, send out information about the internal hosts within the firewall region.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]

 .For example, when a host needs to customize the content of a website for a user, the web application must be written to track the user's progress from page to page.^ A web server may utilize a web application for dynamic web page content.
  • Glossary - Web Application Security Consortium 28 January 2010 0:00 UTC www.webappsec.org [Source type: Reference]

 ^ For example, when a host needs to customize the content of a website for a user, the web application must be written to track the user's progress from page to page.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ User agent URI scheme Web application Uniform Resource Identifier Uniform Resource Locator 890 Visitors Likes ( 171 ) People Who Liked This .
  • http://getglue.com/topics/p/hypertext_transfer_protocol 28 January 2010 0:00 UTC getglue.com [Source type: FILTERED WITH BAYES]

 .A common method for solving this problem involves sending and receiving cookies.^ A common method for solving this problem involves sending and receiving [ cookie|cookies ].
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Sending data using DOT involves communication among the sender, receiver, and the GTC. Figure 3 enumerates the steps in this communication: .
  • An Architecture for Internet Data Transfer 28 January 2010 0:00 UTC www.cs.cmu.edu [Source type: Reference]

 ^ E-mail (Electronic Mail) E-mail is a method for sending and receiving messages between users over a network.
  • SkyPoint Communications - Internet Service Provider - ISP - Minnesota 28 January 2010 0:00 UTC www.skypoint.com [Source type: Reference]

 .Other methods include server side sessions, hidden variables (when the current page is a form), and URL encoded parameters (such as /index.php?session_id=some_unique_session_code).^ Other methods include server side sessions, hidden variables (when the current page is a form ), and URL encoded parameters (such as /index.php?session_id=some_unique_session_code ).
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ As we'll see in later chapters, one of the biggest challenges in HTTP environments, whether content switched or not, is maintaining some form of client-side state that enables Web servers and intermediary devices to recognize the client session and understand the current status of the user session.
  • InformIT: Understanding Application Layer Protocols > HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.informit.com [Source type: FILTERED WITH BAYES]

 ^ Page 46 9.1.2); other methods MUST NOT be automatically retried, although user agents MAY offer a human operator the choice of retrying the request.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

Secure HTTP

.There are currently two methods of establishing a secure HTTP connection: the HTTPS URI scheme and the HTTP 1.1 Upgrade header, introduced by RFC 2817.^ HTTP 1.1 Upgrade header .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ There are currently two methods of establishing a secure HTTP connection: the [ ] URI scheme and the HTTP 1.1 Upgrade header, introduced by RFC 2817.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ After a connection has been established, an HTTP GET request is made.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 .Browser support for the Upgrade header is, however, nearly non-existent, hence the HTTPS URI scheme is still the dominant method of establishing a secure HTTP connection.^ HTTP 1.1 Upgrade header .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Browser support for the Upgrade header is, however, nearly non-existent, hence the [ ] URI scheme is still the dominant method of establishing a secure HTTP connection.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ There are currently two methods of establishing a secure HTTP connection: the [ ] URI scheme and the HTTP 1.1 Upgrade header, introduced by RFC 2817.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 Secure HTTP is notated by the prefix HTTPS:// instead of HTTP://

https URI scheme

Main article: HTTPS
.https is a URI scheme that is, aside from the scheme token, syntactically identical to the http scheme used for normal HTTP connections, but which signals the browser to use an added encryption layer of SSL/TLS to protect the traffic.^ GET Method THTP and HTTP's use of the GET method are identical.
  • draft-gershenfeld-thtp-00 - Trivial Hypertext Transfer Protocol (THTP) 28 January 2010 0:00 UTC tools.ietf.org [Source type: Academic]

 ^ THTP uses HTTP's URI naming scheme.
  • draft-gershenfeld-thtp-00 - Trivial Hypertext Transfer Protocol (THTP) 28 January 2010 0:00 UTC tools.ietf.org [Source type: Academic]

 ^ Defines URI scheme http:.
  • Protocol: HTTP ( HyperText Transfer Protocol ) 28 January 2010 0:00 UTC www.protocolbase.net [Source type: Reference]

 .SSL is especially suited for HTTP since it can provide some protection even if only one side of the communication is authenticated.^ SSL is especially suited for HTTP since it can provide some protection even if only one side of the communication is authenticated .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ HTTPS: is a URI scheme syntactically identical to the http: scheme used for normal HTTP connections, but which signals the browser to use an added encryption layer of SSL / TLS to protect the traffic.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Basic Authentication : A simple form of client-side authentication supported in HTTP. The http-client sends a request header to the web server containing a Base64 encoded username and password.
  • Glossary - Web Application Security Consortium 28 January 2010 0:00 UTC www.webappsec.org [Source type: Reference]

 .This is the case with HTTP transactions over the Internet, where typically only the server is authenticated (by the client examining the server's certificate).^ Typically, an HTTP client initiates a request.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ This is the case with HTTP transactions over the Internet, where typically only the server is authenticated (by the client examining the server's certificate ).
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Each client is both an HTTP client and server.
  • Peer Distributed Transfer Protocol Specification 28 January 2010 0:00 UTC distribustream.org [Source type: Reference]

HTTP 1.1 Upgrade header field

.HTTP 1.1 introduced support for the Upgrade header field.^ HTTP 1.1 Upgrade header .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ HTTP 1.1 introduced support for the Upgrade header.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ However, HTTP/1.1 messages may include a single MIME-Version general-header field to indicate what version of the MIME protocol was used to construct the message.
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .In the exchange, the client begins by making a clear-text request, which is later upgraded to Transport Layer Security (TLS).^ TLS See transport layer security ( TLS ) .
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 28 January 2010 0:00 UTC www.redhat.com [Source type: Reference]

 ^ In the exchange, the client begins by making a clear-text request, which is later upgraded to TLS .
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]

 ^ Transport Layer Security (TLS) protocol.
  • Glossary of Messaging Terms 28 January 2010 0:00 UTC www.as400-email.com [Source type: Reference]

 .Either the client or the server may request that the connection be upgraded.^ The data connection may be in either direction (server-to-user or user-to server).
  • Protocol: FTP - Data ( File Transfer Protocol - Data Protocol ) 28 January 2010 0:00 UTC www.protocolbase.net [Source type: Reference]

 ^ The server may close the connection to prevent the client from continuing the request.
  • WebDev :: Web Developer Resources - Hypertext Transfer Protocol (HTTP) :: University of Memphis 28 January 2010 0:00 UTC www.memphis.edu [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Some may be more specific to either a client or server message."
  • GIAC GCIH Practical - TCP Port 80 HTTP Header Exploitation 28 January 2010 0:00 UTC www.cgisecurity.com [Source type: Reference]

 The most common usage is a clear-text request by the client followed by a server demand to upgrade the connection:
Client:
GET /encrypted-area HTTP/1.1
Host: www.example.com
Server:
HTTP/1.1 426 Upgrade Required
Upgrade: TLS/1.0, HTTP/1.1
Connection: Upgrade
.The server returns a 426 status-code because 400 level codes indicate a client failure (see List of HTTP status codes), which correctly alerts legacy clients that the failure was client-related.^ This pages lists HTTP status codes and their definitions.
  • WebDev :: Web Developer Resources - Hypertext Transfer Protocol (HTTP) :: University of Memphis 28 January 2010 0:00 UTC www.memphis.edu [Source type: FILTERED WITH BAYES]

 ^ Related links: HTTP status codes .
  • Protocol: HTTP ( HyperText Transfer Protocol ) 28 January 2010 0:00 UTC www.protocolbase.net [Source type: Reference]

 ^ The most common usage is a clear-text request by the client followed by a server demand to upgrade the connection, which looks like this: Client: GET /encrypted-area HTTP/1.1 Host: www.example.com Server: HTTP/1.1 426 Upgrade Required Upgrade: TLS/1.0, HTTP/1.1 Connection: Upgrade The server returns a 426 status-code because 400 level codes indicate a client failure (see List of HTTP status codes ), which correctly alerts legacy clients that the failure was client-related.
  • Hypertext transfer protocol encyclopedia topics | Reference.com 28 January 2010 0:00 UTC www.reference.com [Source type: Reference]
The benefits of using this method for establishing a secure connection are:
  • that it removes messy and problematic redirection and URL rewriting on the server side,
  • it allows virtual hosting of secured websites (although HTTPS also allows this using Server Name Indication), and
  • it reduces user confusion by providing a single way to access a particular resource.
.A weakness with this method is that the requirement for a secure HTTP cannot be specified in the URI. In practice, the (untrusted) server will thus be responsible for enabling secure HTTP, not the (trusted) client.^ HTTP Message 4.1 Message Types HTTP messages consist of requests from client to server and responses from server to client.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ Clients aren't required to use them, but HTTP 1.1 servers are required to honor requests that do use them.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 ^ HTTP 1.1 requires a few extra things from both clients and servers.
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

Example session

Below is a sample conversation between an HTTP client and an HTTP server running on www.example.com, port 80.

Client request

 GET /index.html HTTP/1.1
 Host: www.example.com
.A client request is followed by a blank line, so that the request ends with a double newline, each in the form of a carriage return followed by a line feed.^ Request method headers (Carriage Return /Line Feed) message body .
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ End-to-end revalidation may be requested either when the client does not have its own local cached copy, in which case we call it "unspecified end-to-end revalidation", or when the client does have a local cached copy, in which case we call it "specific end-to-end revalidation."
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ The client can specify these three kinds of action using Cache- Control request directives: End-to-end reload The request includes a "no-cache" Cache-Control directive or, for compatibility with HTTP/1.0 clients, "Pragma: no-cache".
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .The "Host" header distinguishes between various DNS names sharing a single IP address, allowing name-based virtual hosting.^ DN See distinguished name ( DN ) .
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 28 January 2010 0:00 UTC www.redhat.com [Source type: Reference]

 ^ Each host has a unique IP address.
  • Protocol: FTP - Data ( File Transfer Protocol - Data Protocol ) 28 January 2010 0:00 UTC www.protocolbase.net [Source type: Reference]

 ^ Bootstrap Protocol (bootp) A TCP/IP protocol allowing a diskless workstation to find its own IP address at startup.
  • http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/glossary/index.html 28 January 2010 0:00 UTC www.redhat.com [Source type: Reference]

 While optional in HTTP/1.0, it is mandatory in HTTP/1.1.

Server response

 HTTP/1.1 200 OK
 Date: Mon, 23 May 2005 22:38:34 GMT
 Server: Apache/1.3.3.7 (Unix)  (Red-Hat/Linux)
 Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
 Etag: "3f80f-1b6-3e1cb03b"
 Accept-Ranges: bytes
 Content-Length: 438
 Connection: close
 Content-Type: text/html; charset=UTF-8
.A server response is followed by a blank line and text of the requested page.^ (Single Blank line ends server response headers).
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ If the server does not wish to accept the credentials sent with a request, it SHOULD return a 401 (Unauthorized) response.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Request A request message from a client to a server includes, within the first line of that message, the method to be applied to the resource, the identifier of the resource, and the protocol version in use.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .The ETag (entity tag) header is used to determine if a cached version of the requested resource is identical to the current version of the resource on the server.^ Entity Tags Entity tags are used for comparing two or more entities from the same requested resource.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ The server MUST NOT use a cached copy when responding to such a request.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Using Web server response headers.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 .Content-Type specifies the Internet media type of the data conveyed by the http message, while Content-Length indicates its length in bytes.^ Content-Length: - indicates the length in octets, of the Entity-Body (Message Body) in decimal.
  • Hypertext Transfer Protocol, HTTP, http header 28 January 2010 0:00 UTC www.rhyshaden.com [Source type: FILTERED WITH BAYES]

 ^ A Content-Type specifies the media type of the underlying data.
  • Hypertext Transfer Protocol -- HTTP/1.0 28 January 2010 0:00 UTC ftp.ics.uci.edu [Source type: Reference]

 ^ Media type of message sent .
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 .The HTTP/1.1 webserver publishes its ability to respond to requests for certain byte ranges of the document by setting the header Accept-Ranges: bytes.^ Otherwise, the byte-range-set is unsatisfiable.
  • RFC 2616 28 January 2010 0:00 UTC www.normos.org [Source type: FILTERED WITH BAYES]

 ^ To comply with HTTP 1.1, clients must include the Host: header with each request accept responses with chunked data either support persistent connections , or include the " Connection: close " header with each request handle the " 100 Continue " response Return to Table of Contents Host: Header .
  • HTTP Made Really Easy 9 February 2010 14:38 UTC www.jmarshall.com [Source type: FILTERED WITH BAYES]

 ^ HTTP/1.1 uses content-coding values in the Accept-Encoding ( section 14.3 ) and Content-Encoding ( section 14.12 ) header fields.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 .This is useful if the client needs to have only certain portions[8] of a resource sent by the server, which is called byte serving.^ The most common form of Request-URI is that used to identify a resource on an origin server or gateway.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ Request A request message from a client to a server includes, within the first line of that message, the method to be applied to the resource, the identifier of the resource, and the protocol version in use.
  • RFC 2068 28 January 2010 0:00 UTC asg.web.cmu.edu [Source type: Reference]

 ^ When sending a PUT request to an HTTP/1.1 server, a client must use at least one of: a valid Content-Length , a multipart Content-Type , or the "chunked" Transfer-Encoding .
  • Hypertext Transfer Protocol -- HTTP/1.1 28 January 2010 0:00 UTC www.graphcomp.com [Source type: Reference]

 .When Connection: close is sent in a header, it means that the web server will close the TCP connection immediately after the transfer of this package.^ The server will automatically terminate the TCP connection immediately after the HTML document has been transferred to the client.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ Using Web server response headers.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

 ^ The server sends an acknowledgment, and the connection is closed.
  • Ch 21 -- Introducing HyperText Transfer Protocol (HTTP) 28 January 2010 0:00 UTC www.podgoretsky.com [Source type: Reference]

See also

References

  1. ^ RFC 2616, Hypertext Transfer Protocol -- HTTP/1.1, R. Fielding, J. Getty, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee (June 1999)
  2. ^ Fielding, et al. "Internet RFC 2616.", section 1.4. Retrieved on January 21, 2009.
  3. ^ webcom.com glossary entry for HTTP/1.1 Webcom.com, Retrieved on May 29, 2009
  4. ^ "Apache Week. HTTP/1.1". http://www.apacheweek.com/features/http11.  090502 apacheweek.com
  5. ^ "Vulnerability Note VU#150227: HTTP proxy default configurations allow arbitrary TCP connections". US-CERT. 2002-05-17. http://www.kb.cert.org/vuls/id/150227. Retrieved 2007-05-10. 
  6. ^ HTTP 1.1 Section 5.1.1
  7. ^ 6.1 Status-Line
  8. ^ Tools.ietf.org, Byte Range Retrieval Extension to HTTP

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