The Hypertext Transfer Protocol (HTTP) is an Application Layer Application Layer is a term used in categorizing protocols and methods in architectural models of computer networking. Both the OSI model and the Internet Protocol Suite define application layers protocol In computing and telecommunications, a protocol or communications protocol is a formal description of message formats and the rules for exchanging those messages. Protocols may include signaling, authentication and error detection and correction capabilities. In its simplest form, a protocol can be defined as the rules governing the syntax, for distributed, collaborative, hypermedia information systems.^[1]

HTTP is a request-response Request-response, also known as request-reply, is a message exchange pattern in which a requestor sends a request message to a replier system which receives and processes the request, ultimately returning a message in response. This is a simple, but powerful messaging pattern which allows two applications to have a two-way conversation with one standard typical of client-server Client–server model of computing is a distributed application structure that partitions tasks or workloads between service providers, called servers, and service requesters, called clients. Often clients and servers communicate over a computer network on separate hardware, but both client and server may reside in the same system. A server computing. In HTTP, web browsers A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content. Hyperlinks present in resources enable users to easily navigate their browsers to or spiders A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants, automatic indexers, bots, or Web spiders, Web robots, or—especially in the FOAF community—Web scutters typically act as clients, while an application running on the computer hosting the web site A website is a collection of related web pages, images, videos or other digital assets that are addressed relative to a common Uniform Resource Locator (URL), often consisting of only the domain name, or the IP address, and the root path ('/') in an Internet Protocol-based network. A web site is hosted on at least one web server, accessible via a acts as a server. The client, which submits HTTP requests, is also referred to as the user agent A user agent is a client application implementing a network protocol used in communications within a client–server distributed computing system. The term most notably refers to applications that access the World Wide Web, but other systems, such as the Session Initiation Protocol , use the term user agent to refer to both end points of a. The responding server, which stores or creates resources such as HTML HTML, which stands for HyperText Markup Language, is the predominant markup language for web pages. It provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes and other items. It allows images and objects to be embedded and can be used to create interactive forms files and images, may be called the origin server. In between the user agent and origin server may be several intermediaries, such as proxies In computer networks, a proxy server is a server that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. The proxy server evaluates the request according to, gateways Gateways, also called protocol converters, can operate at any layer of the OSI model. The job of a gateway is much more complex than that of a router or switch. Typically, a gateway must convert one protocol stack into another, and tunnels Computer networks use a tunneling protocol when one network protocol encapsulates a different payload protocol. By using tunneling one can (for example) carry a payload over an incompatible delivery-network, or provide a secure path through an untrusted network.

HTTP is not constrained in principle to using TCP/IP The Internet Protocol Suite is the set of communications protocols used for the Internet and other similar networks. It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking protocols defined in this standard. Today's IP networking, although this is its most popular implementation platform. Indeed HTTP can be "implemented on top of any other protocol on the Internet, or on other networks." HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used.^[2]

Resources The concept of resource is primitive in the Web architecture, and is used in the definition of its fundamental elements. The term was first introduced to refer to targets of Uniform Resource Locators , but its definition has been further extended to include the referent of any Uniform Resource Identifier (RFC 3986), or Internationalized Resource to be accessed by HTTP are identified using Uniform Resource Identifiers In computing, a Uniform Resource Identifier is a string of characters used to identify a name or a resource on the Internet. Such identification enables interaction with representations of the resource over a network (typically the World Wide Web) using specific protocols. Schemes specifying a concrete syntax and associated protocols define each (URIs)—or, more specifically, Uniform Resource Locators In computing, a Uniform Resource Locator is a Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it. In popular usage and in many technical documents and verbal discussions it is often incorrectly used as a synonym for URI,. The best-known example of a URL is the " (URLs)—using the http or https Hypertext Transfer Protocol Secure is a combination of the Hypertext Transfer Protocol with the SSL/TLS protocol to provide encryption and secure (website security testing) identification of the server. It uses port 443. HTTPS connections are often used for payment transactions on the World Wide Web and for sensitive transactions in corporate URI schemes In the field of computer networking, a URI scheme is the top level of the Uniform Resource Identifier naming structure. All URIs and absolute URI references are formed with a scheme name, followed by a colon character (":"), and the remainder of the URI called (in the outdated RFCs 1738 and 2396, but not the current STD 66/RFC 3986) the.

Its use for retrieving inter-linked resources, called hypertext Hypertext is text displayed on a computer or other electronic device with references to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Apart from running text, hypertext may contain tables, images and other presentational devices. Hypertext is the underlying concept defining the structure of the documents, led to the establishment of the World Wide Web The World Wide Web, abbreviated as WWW and commonly known as the Web, is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them by using hyperlinks. Using concepts from earlier hypertext systems, British in 1990 by English physicist Tim Berners-Lee Sir Timothy John "Tim" Berners-Lee, OM, KBE, FRS, FREng, FRSA , is a British engineer and computer scientist and MIT professor credited with inventing the World Wide Web, making the first proposal for it in March 1989. On 25 December 1990, with the help of Robert Cailliau and a young student at CERN, he implemented the first successful.

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. Hence HTTP/1.1 may be faster as it takes time to set up such connections.

The standards development of HTTP has been coordinated by the World Wide Web Consortium The World Wide Web Consortium is the main international standards organization for the World Wide Web (abbreviated WWW or W3) and the Internet Engineering Task Force The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standards bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite. It is an open standards organization, with no formal membership or membership requirements. All participants and managers are (IETF), culminating in the publication of a series of Requests for Comments In computer network engineering, a Request for Comments is a memorandum published by the Internet Engineering Task Force (IETF) describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems (RFCs), most notably RFC 2616 (June 1999), which defines HTTP/1.1, the version of HTTP in common use.

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. In March 1996, one web hosting company reported that over 40% of browsers in use on the Internet were HTTP 1.1 compliant. That same web hosting company reported that by June 1996, 65% of all browsers accessing their servers were HTTP/1.1 compliant.^[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. An HTTP client initiates a request. It establishes a Transmission Control Protocol The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite (the other being Internet Protocol, or IP), so the entire suite is commonly referred to as TCP/IP. Whereas IP handles lower-level transmissions from computer to computer as a message makes its way (TCP) connection to a particular port In computer networking, a port is an application-specific or process-specific software construct serving as a communications endpoint used by Transport Layer protocols of the Internet Protocol Suite, such as Transmission Control Protocol and User Datagram Protocol (UDP). A specific port is identified by its number, commonly known as the port on a host (typically port 80; see List of TCP and UDP port numbers In computer networking, the protocols of the Transport Layer of the Internet Protocol Suite, most notably the Transmission Control Protocol and the User Datagram Protocol (UDP), but also other protocols, use a numerical identifier for the data structures of the endpoints for host-to-host communications. Such an endpoint is known as a port and the). An HTTP server listening on that port waits for a client's request message. 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.

Request message

The request message consists of the following:

• Request line, such as GET /images/logo.png HTTP/1.1, which requests a resource called /images/logo.png from server
• Headers HTTP Headers form the core of an HTTP request, and are very important in an HTTP response. They define various characteristics of the data that is requested or the data that has been provided. The headers are separated from the request or response body by a blank line. HTTP headers can be near-arbitrary strings, but only some are commonly, 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 Originally, carriage return was the term for the control character in Baudot code on a teletypewriter for end of line return to beginning of line and did not include line feed. Later it was used for a mechanism or lever on a typewriter that would cause the cylinder on which the paper was held to return to the left side of the paper after a line of followed by a line feed In computing, a newline, also known as a line break or end-of-line character, is a special character or sequence of characters signifying the end of a line of text. The name comes from the fact that the next character after the newline will appear on a new line—that is, on the next line below the text immediately preceding the newline. The). The empty line must consist of only <CR><LF> and no other whitespace As is common in technical literature, the two words "white space" have found widespread usage as the single term "whitespace", especially when used as an adjective, as in "whitespace character". Some specifications refer to "white space" while others refer to "whitespace"; there is no difference. In the HTTP/1.1 protocol, all headers except Host are optional.

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.^[4]

Request methods

HTTP defines eight methods (sometimes referred to as "verbs") indicating the desired action to be performed on the identified resource. What this resource represents, whether pre-existing data or data that is generated dynamically, depends on the implementation of the server. Often, the resource corresponds to a file or the output of an executable residing on the server.

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 In system software, a web application is an application that is accessed over a network such as the Internet or an intranet. The term may also mean a computer software application that is hosted in a browser-controlled environment [citation needed] or coded in a browser-supported language (such as JavaScript, combined with a browser-rendered. One reason for this is that GET may be used arbitrarily by robots Internet bots, also known as web robots, WWW robots or simply bots, are software applications that run automated tasks over the Internet. Typically, bots perform tasks that are both simple and structurally repetitive, at a much higher rate than would be possible for a human alone. The largest use of bots is in web spidering, in which an automated or crawlers A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants, automatic indexers, bots, or Web spiders, Web robots, or—especially in the FOAF community—Web scutters, which should not need to consider the side effects that a request should cause. See safe methods below.

POST In computing, a POST message is a type of HTTP request message. It is used when the request should result in an action on the server which has side effects. For example, when submitting a form to buy something on a website a POST method is normally used

Submits data to be processed (e.g., from an HTML form A webform on a web page allows a user to enter data that is sent to a server for processing. Webforms resemble paper forms because internet users fill out the forms using checkboxes, radio buttons, or text fields. For example, webforms can be used to enter shipping or credit card data to order a product or can be used to retrieve data) to the identified resource. The data is included in the body of the request. This may result in the creation of a new resource or the updates of existing resources or both.

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 In computing, a Uniform Resource Locator is a Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it. In popular usage and in many technical documents and verbal discussions it is often incorrectly used as a synonym for URI,. The best-known example of a URL is the ". This can be used to check the functionality of a web server by requesting '*' instead of a specific resource.

CONNECT

Converts the request connection to a transparent TCP/IP tunnel Computer networks use a tunneling protocol when one network protocol encapsulates a different payload protocol. By using tunneling one can (for example) carry a payload over an incompatible delivery-network, or provide a secure path through an untrusted network, usually to facilitate SSL Transport Layer Security and its predecessor, Secure Socket Layer (SSL), are cryptographic protocols that provide security for communications over networks such as the Internet. TLS and SSL encrypt the segments of network connections at the Transport Layer end-to-end-encrypted communication (HTTPS) through an unencrypted HTTP proxy In computer networks, a proxy server is a server that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. The proxy server evaluates the request according to.^[5]

PATCH

Is used to apply partial modifications to a resource.^[6]

HTTP servers are required to implement at least the GET and HEAD methods^[7] and, whenever possible, also the OPTIONS method.^{[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. In other words, they should not have side effects In computer science, a function or expression is said to have a side effect if, in addition to producing a value, it also modifies some state or has an observable interaction with calling functions or the outside world. For example, a function might modify a global or a static variable, modify one of its arguments, raise an exception, write data, beyond relatively harmless effects such as logging A server log is a log file automatically created and maintained by a server of activity performed by it, caching In computer science, a cache is a component that improves performance by transparently storing data such that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere. If requested data is contained in the, the serving of banner advertisements A web banner or banner ad is a form of advertising on the World Wide Web. This form of online advertising entails embedding an advertisement into a web page. It is intended to attract traffic to a website by linking to the website of the advertiser. The advertisement is constructed from an image , JavaScript program or multimedia object employing or incrementing a web counter A web counter or hit counter is a computer software program that indicates the number of visitors, or hits, a particular webpage has received. Once set up, these counters will be incremented by one every time the web page is accessed in a web browser. Making arbitrary GET requests without regard to the context of the application's state should therefore be considered safe.

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 Electronic commerce, commonly known as e-commerce or eCommerce, or e-business consists of the buying and selling of products or services over electronic systems such as the Internet and other computer networks. The amount of trade conducted electronically has grown extraordinarily with widespread Internet usage. The use of commerce is conducted in or transmission of email Electronic mail, commonly called email or e-mail, is a method of exchanging digital messages across the Internet or other computer networks. Email systems are based on a store-and-forward model in which email server computer systems accept, forward, deliver and store messages on behalf of users, who only need to connect to the email infrastructure,. Such methods are therefore not usually used by conforming web robots Internet bots, also known as web robots, WWW robots or simply bots, are software applications that run automated tasks over the Internet. Typically, bots perform tasks that are both simple and structurally repetitive, at a much higher rate than would be possible for a human alone. The largest use of bots is in web spidering, in which an automated or web crawlers A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants, automatic indexers, bots, or Web spiders, Web robots, or—especially in the FOAF community—Web scutters, which tend to make requests without regard to context or consequences.

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. This is discouraged, because it can cause problems for Web caching Web caching is the caching of web documents in order to reduce bandwidth usage, server load, and perceived lag. A web cache stores copies of documents passing through it; subsequent requests may be satisfied from the cache if certain conditions are met, search engines and other automated agents, which can make unintended changes on the server.

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. Methods GET, HEAD, OPTIONS and TRACE, being prescribed as safe, should also be idempotent, as HTTP is a stateless protocol.

In 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). 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. 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.

Note that whether a method is idempotent is not enforced by the protocol or web server. 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. 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.

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 way the user agent handles the response primarily depends on the code and secondarily on the response headers. 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.^[8]

Also, the standard reason phrases are only recommendations and can be replaced with "local equivalents" at the web developer's discretion. 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 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.

Persistent connections

In HTTP/0.9 and 1.0, the connection is closed after a single request/response pair. In HTTP/1.1 a keep-alive-mechanism was introduced, where a connection could be reused for more than one request.

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.

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. HTTP pipelining further reduces lag time, allowing clients to send multiple requests before a previous response has been received to the first one. 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.

HTTP session state

HTTP is a stateless protocol. The advantage of a stateless protocol is that hosts do not need to retain information about users between requests. 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 common method for solving this problem involves sending and receiving cookies. 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).

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. Browser support for the Upgrade header is, however, nearly non-existent, so HTTPS is still the dominant method of establishing a secure HTTP connection. Secure HTTP is notated by the prefix https:// instead of http:// on web URIs.

https URI scheme

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. SSL is especially suited for HTTP since it can provide some protection even if only one side of the communication is authenticated. 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).

HTTP 1.1 Upgrade header field

HTTP 1.1 introduced support for the Upgrade header field. In the exchange, the client begins by making a clear-text request, which is later upgraded to Transport Layer Security (TLS). Either the client or the server may request that the connection be upgraded. 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.

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.

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. The "Host" header distinguishes between various DNS names sharing a single IP address, allowing name-based virtual hosting. 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. 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. Content-Type specifies the Internet media type of the data conveyed by the http message, while Content-Length indicates its length in bytes. 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. This is useful if the client needs to have only certain portions^[9] of a resource sent by the server, which is called byte serving. 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.

See also

• Basic access authentication
• Content negotiation
• Curl-loader - HTTP/S loading/testing open-source SW
• Digest access authentication
• HTTP compression
• HTTP-MPLEX
• HTTP(P2P)
• Hxxp
• List of computer standards
• List of file transfer protocols
• List of HTTP headers
• List of HTTP status codes
• Representational State Transfer (REST)
• Web cache
• WebDAV

References

1. ^ Fielding, Roy T.; Gettys, James; Mogul, Jeffrey C.; Nielsen, Henrik Frystyk; Masinter, Larry; Leach, Paul J.; Berners-Lee (June 1999). "RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1". http://tools.ietf.org/html/rfc2616.
2. ^ Fielding, et al. "Internet RFC 2616.", section 1.4. Retrieved on January 21, 2009.
3. ^ "HTTP/1.1". Webcom.com Glossary entry. http://www.webcom.com/glossary/http1.1.shtml. Retrieved 2009-05-29.
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. ^ Dusseault, Lisa; Snell, James M.. "RFC 5789: PATCH Method for HTTP". http://tools.ietf.org/html/rfc5789.
7. ^ HTTP 1.1 Section 5.1.1
8. ^ 6.1 Status-Line
9. ^ Tools.ietf.org, Byte Range Retrieval Extension to HTTP

Further reading

• HTTP 0.9 - As Implemented in 1991

External links

• Bulkcheck HTTP-Headers from different URLs simultaneously
• Watch HTTP Client/Server Request/Responses
• HTTP header bookmarklet
• Eclipse HTTP Client - HTTP4E: a commercial Eclipse IDE plugin to execute/test/debug HTTP calls.
• Web based HTTP session viewer

Categories: Semantic Web | HTTP | Web browsers | Application layer protocols | World Wide Web | Open formats | World Wide Web Consortium standards

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• Gopher Protocol: Encyclopedia
• Internet Protocol: Encyclopedia
• File Transfer Protocol: Encyclopedia
• Hypertext Markup Language: Encyclopedia
• Computers: Internet: Domain Names: For Sale or Auction: Transfer and Escrow Services: Directory

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