Page 25 - DCAP408_WEB_PROGRAMMING

Unit 1: Internet Fundamentals

backtrack to previous visited node, or to move the very first visited node, could be regarded as Notes
part of basic process submodel.

1.8 HTTP (Hypertext Transfer Protocol)

The standard Web transfer protocol is HTTP. It transmits hypertext over networks. The name is
somewhat misleading in that HTTP is not a protocol for transferring hypertext; rather, it is a
protocol for transferring information with the efficiency necessary for making hypertext jumps.
The data transferred by the protocol can be plain text, hypertext, audio, images or any other
Internet accessible information.
The HyperText Transport Protocol (HTTP) is an application-level Protocol used by Web
client and Web servers to communicate with each other. HTTP has been in use since 1990.
The HTTP is a transaction-oriented client/server protocol. To provide reliability, HTTP
makes use of TCP. Although the use of TCP for the transport connection is very common,
it is not formally required by the standard. As and when ATM networks become
commercially available the HTTP requests, replies can be carried in AAL5 just as well.HTTP
is a “stateless” protocol. Each transaction is treated independently. Therefore, a typical
implementation will create a TCP new connection between client and server for each
transaction and then terminate the connection as soon as the transaction is complete. Each
interaction consists of one ASCII request, followed by one RFC 822 MIME-like response
i.e., Messages are in a format similar to that used by Internet Mail and the Multipurpose
Internet Mail Extensions (MIME).

Task HTTP is constantly evolving, several versions are in use and others are under
development. Analyse
The World Wide Web provides a single interface for accessing all these protocols. This creates a
convenient and user-friendly environment. It is no longer necessary to be conversant in these
protocols within separate, command-level environments. The Web gathers, together these
protocols into a single system. Because of this feature, and because of the Web’s ability to work
with multimedia and advanced programming languages, the World Wide Web is the fastest-
growing component of the Internet.

1.8.1 Understanding Hypertext Transport Protocol (HTTP)

HTTP is a request/response protocol. A web client establishes a connection with a Web server
and sends a resource request. The request contains a request method, protocol version, followed
by a MIME-like message. The message contains request modifiers, client information, and possible
body content.
The Web server responds with a status line, including the message’s protocol version and a
success or error code. It is followed by a MIME-link message containing server information,
entity meta-information, and possible body content. Figure 1.6 shows where the HTTP layer fits
into Web client and servers.

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