Page 197 - DCAP406_DCAP_207_Computer Networks

Computer Networks/Networks

Notes together are the hypertext and the hyperlinks. The hyperlink allows electronic files on the Web
to be linked so you can jump easily between them using hypertext protocol. As you have learnt
that web browsers that enables you to access the Web also distinguish between web pages and
other types of data on the Internet because web pages are written in a computer language called
Hypertext Markup Language or HTML.
Hypertext: The operation of the www is based on hypertext through which it interacts with web
users or web browsers. Like normal text, the hypertext can be stored, read, searched or edited. It
differs from the normal text that hypertext contains connections within the text to other
documents. The hypertext links are used to create hyperlinks that can further create a complex
virtual web of connections. The hypertext enables the web user to go forward or back, get much
more detail on the current topic, change direction and navigate in any way that the web user
desires wile surfing webpages instead of following text in a liner fashion like a book. This is
possible because hypertext has text with pointers to other text.

Hypermedia: It is hypertext with some differences. The hypermedia documents not only provide
links to other pieces of text, but it also provides link to other forms of media like sounds, images
and movies. In other words, the hypermedia is used to combine hypertext and multimedia.

!
Caution Hypermedia and hypertext are similar in concept but yet different. Hypermedia
is considered as a superset of hypertext.

12.3.1 WWW Functioning

World Wide Web is software that works in the client-server architecture in which web browser
is a web client and web server that serves requests raised by the web client is called the server.
The client is a browser like Internet Explorer, Netscape Navigator or Mozilla. Browsers are used
to interact with the server using a set of instructions called protocols. These protocols facilitate
in the accurate transfer of data through requests from a browser and responses from the server.
Many protocols exist on the Internet for communication among several hosts. The World Wide
Web is a part of the Internet and puts all these protocols under one group. They may be HTTP,
FTP, Telnet, e-mail etc. The www employs a connectionless protocol.

The client server model uses a distributed architecture in which a client program may be running
on a completely separate machine from that of the server possibly in another room or even in
another country. In such case, the task of document storage is left to the server and the task of
document presentation is left to the client so that each program can progress independent to
each other. The web client is invoked and the web user selects a hyperlink in a piece of hypertext
connecting to another document. The web browser uses the address associated with that hyperlink
to connect to the web server at a specified network address and requests for the document.

The server responds back by sending the text and any other media within that text to the client
browser, which the browser presents on the user’s screen. The World Wide Web involves
thousands of such virtual transactions per hour across the world and thus creating a web of
information flow. The web servers are being equipped with encryption and client authentication
abilities in which they will be able to send and receive secure data. The protocol used by the web
clients and web servers to communicate with each other is called the HTTP. The webpages that
are returned back use a programming language known as the Hypertext Markup Language
(HTML).

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